The old thread asking for technology feedback (with GoogleDocs) is out of date, listing technologies that do not exist any more. I figured I would initiate a more up-to-date conversation on the topic.
Era I
Economy and Population
Open-Pit Mine - Depends on your starting location to how important this tech is, but I usually research it. Often in Era I, sometimes Era II. It is a solid tech.
Empire Mint - Must have! This is always one of my priority Era I technologies and something every single faction needs. It results in one of the priority buildings for every single new city you found.
Aquapulvistics - This is a good, well-balanced technology. Depending on random map generation and faction, it can be either extremely important or not important at all. I always stop to evaluate this technology, but do not always research it.
Seed Storage - Almost must have. Unless I am playing Broken Lords, I will always research this technology, and I usually research it in Era I. The building is rarely my HIGHEST priority, but one that most cities I found will have early on.
Military
Mercenary Market - A good technology. I personally rarely use Mercenaries, but the Heroes are well worth consideration. It is not an essential technology (except for some factions/quests), but usually a solid choice. An AI Roving Clans can completely invalidate it making it not worth researching, which is a flaw in the game's AI rather than the technology.
Military Science - Probably the worst Era I technology and one I never research. Fortifications are meaningless and the extra Militia is completely useless. There is no reason to research this.
Empire and Expansion
Sewer System - Must have. Every faction generates expansion disapproval and needs sources of approval: this is the quickest and easiest way to gain it. It is not the highest Era I priority, and I often put it off until Era II, but I always research this.
Search Party - Completely worthless. There is no way I would waste a research slot on something that (a) has a nebulous benefit and (b) slightly improves the quality of freebies I pick up. This is the only Tier I technology that does not offer the potential of a lasting and meaningful benefit.
Language Square - A good technology. It is not essential, as it is often quicker and easier to just attack villages, but this is always worthy of consideration. Some factions require this for their main quest, however, which can make it a much higher priority than it otherwise would have been. If I do not *need* it, it is usually a low-priority but still desirable Era I technology.
Science and Industry
Public Library - Must have. This is always one of my priority technologies to research (usually first or second) and results in one of the highest priority buildings for every single new city you found. I cannot think of a single situation where you would not take this technology.
Alchemist's Furnace - Almost must have. If the random map gods have turned against you and there is no Glasssteel or Titanium for miles, you may not pick this up. You may also just quit the game and try again! This is usually one of the last Era I technologies I research, as it becomes vital in the mid-game.
Advanced Alloys & Armour - Essentially worthless. You simply lack the resources to use these in Era I, and they are completely invalidated by Era II technologies. I see no reason to ever research these, even with Vaulters who potentially COULD use them would still be better off waiting the few turns for Era II.
Geomic Labs - Another good technology. Depending on location and faction it could be worthless or highly valuable. I always consider whether or not to pick it up, but do not always take it and almost never make it a high priority. If I do pick it up, I usually do so in Era II.
Mill Foundry - Almost must have. If you have a Dust-heavy economy (eg Broken Lords) this can be passed over, but most factions and situations will make this one of my two highest priority technologies. The building is invaluable and usually the first I construct in any new city.
Era II
Economy and Population
Imperial Coinage - I rarely research this technology. Only the final-tier strategic resources are hard to pick up in your own empire and the AI Roving Clans will inevitably ban you before you need this technology. If both Market technologies were rolled in together, and the AI improved, this would be more appealing to me.
Aquacultural Science - An interesting technology. Depending on location and faction it could be completely useless, and I rarely find myself in a situation where I am desparate for more food, but when I have a lot of costal/river cities and not enough growth (eg perhaps I went into a desert for Dust) then this technology becomes highly attractive.
Public Granary - Generally a more appealing option than the previous technology, but still a low-priority that I do not always research. It falls under the 'one last technology to break into Era III' category for me. Worth having, but not worth having over other, higher-priority technologies.
Prisoners, Slaves and Volunteers - A great technology. I do not always pick it up. In fact, I rarely do, but it enables an alternative play using Dust in place of Production. Anything that enables alternative strategies but is not vital to be successful is a perfect technology in my opinion!
Military
Conscription Centre - I never, ever research this. The slight head-start on experience is OK, but by itself is not worth considering. It would perhaps be a more interesting option if it were rolled into another technology.
Meritocratic Promotion - Must have! I cannot imagine a faction or playstyle where you would not pick this, as doing so would surely gimp you against every other player or AI in the game. This is perhaps the definition of a bad technology, as you HAVE to research it to be viable.
Empire and Expansion
Central Market - Must have! Every faction needs approval, and every faction benefits from increased growth when approval is high. I cannot imagine a situation where I would not research this.
Glory of Empire - A good technology. Not every faction/situation requires this, but most benefit from it. I always evaluate whether or not to pick this up and usually do, but it is neither must have nor rarely have.
Native District - Another good technology. Generally speaking, asimilating a second minor faction is worth an Era II technology, but not every faction needs this and not every situation benefits it. It is not unusual for me to leave this until a later Era to pick up, but sometimes the stars align and I have a lot of villages of two desirable minor factions in my early-game Empire and I prioritise this.
Diplomat's Manse - At present, I rarely pick up this technology. It is not a question of the technology itself, but the current poor state of the AI and diplomacy in general. Once they improve, this will become a significantly more appealing option.
Shipyard - At present, this is a highly situational technology and highly uninteresting. Depending on the map generated, it could be required immediately, required later, or completely worthless. It is always a boring technology too, so I never relish situations where I have to research it.
Imperial Highways - Roads and trade routes need to be better explained to new players, as these are a little vague on your first game. I pretty well always research this technology and it is usually a high priority for me in Era II. Roads are too useful to pass up and trade routes are highly desirable. It seems to be exceedingly rare when I can trade with another faction, however. I am not sure if this is an AI issue, or an issue with the design of trade routes, but I would like to see this enhanced in future versions of the game. Watchtowers, on the other hand, are currently terrible. They are obsoleted later on, but you cannot upgrade them. This really needs to be rectified, either by them automatically upgrading when you research the relevant technology, or having a (very cheap) option to upgrade old towers when new ones are available.
Science and Industry
Management Sciences - An interesting technology. I rarely pick it up, but it has the potential to be extremely valuable to most factions. +1 on all tiles is poor when you get it, but once your city grows it has the potential to be extremely valuable. +1 on Forest is, by itself, a fairly poor option, but the two combine quite well. Far from essential, but situationaly creates an important boost to the empire.
Alchemical Alloys & Armour - A solid option. I do not always research either of these, but I usually do. With certain factions (eg Vaulters) I prioritise it, while others I will hold off until later. The armour is a lower priority than the weapons in my mind. Without the armour, units are already (mostly) very sturdy and doing enough damage is the bigger challenge and the cost per unit gets too high if you add armour as well, though the accessories for Heroes can be invaluable.
Alchemy Workshop - A good technology. I do not always research it, and it is not always the highest priority, but it is usually too good to pass up. If you do not keep your research as high as everyone else, you will be severely disadvantaged, and this technology can make or break your empire.
Canal System - An average technology. I very rarely research this, as Management Sciences is superior in every situation and the benefits are too small to make a meaningful difference. +1 on only some tiles only during Summer is a very weak option.
Era III
Economy and Population
Reaping Station - A solid technology and usually a high-priority in this Era. By this time, your empire should be large enough to have multiple resources from this tier within, and they are almost always worth having.
Dust Refinery - Must have. Every faction needs Dust. The more Dust you have, the more flexible your empire will be. A strong boost like this is impossible to pass over.
Dust Depository - This is a really interesting technology, and a concept I think has been underutilised in the tech tree. If you have a large population and dedicate a lot of them to Dust, this is valuable. Otherwise, it varies between an OK option and a poor option. A solid enabler technology!
Plow Factory - This is a really solid technology. I rarely take it, as I rarely need that much extra growth, but it can open up certain locations that would have otherwise been undesirable. A high-Science frozen wasteland or a high-Dust desert could be undesirable options if you cannot support a population worth mentioning, but this technology makes those scenarios more palatable. I rarely use it, but I love it when I do!
Military
Borough Government - Another worthless military technology I never use. Fortifications are meaningless and I have never needed to increase the health regen of garisoned troops --- battles tend to be too decisive for such things.
Empire and Expansion
Bread and Circuses - Almost must have. I always evaluate this one when it comes up. If I need it asap, I pick it up as a priority. If I am doing fine at the moment, I wait until later in the game. I very rarely skip it altogether.
National Museum - I very rarely take this. I usually have enough Influence without it, but it is fairly important in a Diplomatic Victory, especially for Drakken. It is not useless, but perhaps a little under-valued at the moment. This is probably because Diplomacy needs to be improved to make Influence more important.
Highway Outposts - A good technology I usually prioritise. The extra trade route and increased Dust is worth consideration, and this is the point where Towers become worth producing (and they usually only take 1 turn now).
Cargo Docks - An interesting technology, but very situational. The costal district can be useful, and the coastal trade route is potentially profitable (though rarely so in my experience). Never a must-have, but also never a priority. I tend to use this as a situational filler technology, just to unlock an era, but I find the benefits a little on the weak side.
Science and Industry
Statistical Methods - A good technolgy. By this point it is not essential for all games, but vital to a Scientific Victory and not undesirable for other victory conditions.
Smelting Station - Practically an essential technology. Most empires will have several sources of both resources, and both will become vital later in the game, so this tends to be one of my highest priority Era III technologies.
Uncommon Alloys & Armour - Not a bad technology, but not a high priority either. You will hit Era IV before you have the resources to benefit from this (unless you are the Vaulters or have asimilated Silic villages, when this could move up the priority list a little). As before, the weapons are more valuable than the armour, but the accessories are valuable.
Fluid Biomechanics - This is a highly situational technology. If I am going for a Scientific Victory and have many costal or river-front cities, this is worth researching. Outside that very narrow situation, it is not really worth consideration. Replacing it with a tech similar to Dust Depository would make it a far more appealing option without making it must-have.
Unskilled Labour - I have a love-hate relationship with this. If I do not research enough building technologies, I have cities sitting around wasting production. That said, I have found stockpiles to be thoroughly underwhelming. Honestly, I would rather see this broken up and merged into three different techs that do this AND something more interesting. For example, a tech where you get +4 Food/pop AND can use production to make Food stockpiles (and the same for Science and Industry).
Era IV
Economy and Population
Advanced Harvester - In most games you have enough of these resources available to justify this technology, and they are usually worth having if you can get them. I usually pick it up as a priority.
Isolation Sciences - This is an interesting technology. The buildings it unlocks are well worth consideration, but it is not a priority in every game you play. I always evaluate it and often pick it up, but its value tends to vary on how much Winter impacts on my cities' growth.
[u]Neutrition Chemistry[/i] - While not a bad technology, I very rarely research this. I rarely need this much extra growth and, by this point in the game, I am usually well enough established that the technology will make very little impact on my game.
Military
Brigade System - A dull, but effective, technology. I never prioritise this, but will usually pick it up as a filler-technology to advance to the next Era.
Mercenary Corps - I have never used this, but I rarely use Mercenaries either. The basic concept is fine, but it has never entered my game plan.
Signal Corps - This is a good technology. By this point in the game, it is not essential, but a heavily militaristic game will strongly benefit from it. I do not always take it, but often do.
Army Manual - I have never researched this. The experience boost is solid and gives new units a great head-start, but it is just not a priority for me, particularly by this point in the game where my troops are either veterans or I am strugging to hold on.
Empire and Expansion
Cultural Indoctination - A little situational, but always worth consideration. You will always have one minor faction worth asimilating; often two. Three depends a little on your luck. If you do, this can be a valuable technology, but if luck has been against you it is not worth the investment.
Endless Mechanisms - I never bother with this technology. I have no interest in the ability to search ruins a second time at this point in the game (I have much higher priorities with my time). Increased movement on roads is nice, but not worth it by itself.
Hospitality Den - At present, only worth picking up for a Drakken Diplomatic Victory. Diplomacy and the AI both need a major overhaul before this technolgy will be worth consideration under a more general scenario.
Science and Industry
Production Line - I generally skip this technology. It is too little, too late. By this point in the game, either my cities are well established or this small bonus will not be enough to help. For a Wonder Victory it is worth picking up, just to milk every little advantage you can, but otherwise it is not valuable enough.
Rare Metal Foundry - This can rely a little too much on luck for my liking. Some games, my empire has multiple sources of both resources. Others, there is none of them available except for one small corner of the map, deep in another faction's empire. If you are lucky, it is must-have; if unlucky, shrug.
Rare Alloys & Armour - I rarely pick these up. You do not always have the resources required, and you may very well have won the game before you have enough of them to spare. If you are lucky and have the resources coming in fast enough, it can be worth consideration, but this situation happens too rarely to pick this up in most games.
Organised Labour - Another stockpile technology. Honestly, I do not see the point of having two technologies that unlock the same basic concept. Either one tech, or three techs for the different types of stockpiles, then perhaps make stockpiles more valuable in general. As it stands, I rarely bother with this technology, only taking it as a filler.
Borer's Guild - This is a good technology! It is not something I always research, but I will always consider it. The boosted strategic resources alone can make it valuable, with the boosted Industry a little gravy on the side. It is not essential, but good enough to make a difference in the late game.
Imperial Funding - A little situational. If I am aimimg for a Scientific Victory, it is extremely solid! Otherwise, it is usually not a priority at this point in the game.
Era V
Economy and Population
Improved Dust Alchemies - A good option. Pretty well essential for an Economic Victory, or Broken Lords in general, but too late in the game for other situations.
Town Criers - A solid option for any faction or situation at this late point in the game, but probably not a priority technology.
Military
Innoculation Station - A weak option. I do not find the increased regen matters and the extra experience this late in the game is unlikely to make a difference.
[u]Military Reserves[/i] - Completely worthless. Fortifications and Militia are both worthless, hence why players say that the defender lacks an appropriate advantage in this game.
Empire and Expansion
Arts Council - Usually a priority technology for me. By this point, you likely have an extensive empire and can use every source of approval you can get. The additional benefits are gravy and complement the earlier Market technology well.
Imperial News Network - Usually one of my highest priotity technologies at this point, providing both approval and a general bonus that benefits any game plan.
[u]State-Approved Theatre[/i] - Perhaps a little dull at this point in the game, but usually important enough to be worth investing in.
Aura of Empire - I almost never research this. The benefits are too small, too situational and far too late in the game.
Arena of Champions - I never research this. The benefits are far too situational and are unlikely to make a meaningful difference at this late point in the game.
Enlightened Trade - The extra trade route is usually worth investing in this, and the science boost is valuable to a Scientific Victory, but this technology comes too late to be relevant in most games.
Science and Industry
Advanced Quarry - I have never researched this. I may not have a district with a strategic resource, and even if I do I probably do not need +50 Production on my city (which likely has over 1000 at this point). Too little, too situational, too late.
Scientific Specialisation - Essential to a Scientific Victory, but otherwise not a priority at this point in the game.
Marvelous Alloys & Armour - Generally speaking, this is worth researching. By this point of the game you will have plenty of Adamandian and Paladium and your military may need the edge. That said, I usually only bother with the weapons, as the armour is unlikely to matter by this point in the game. It is hard to kill things this late in the game, not keep them alive, and the cheaper, lower-tier armour (or even just Dust Armour) is likely more appealing at this stage.
Era VI
Most technologies in this era are only linked to the Scientific Victory and not worth consideration in general discussion. Most games will be won under another victory condition before you reach these. Ultimately, they are all extremely boring and take far too long to research, making the Scientific Victory a really dull option.
Faction Specific Technologies
Ardent Mages - The pillar/spell technologies are fantastic and make this a really interesting faction. At first, I thought it was a bit much having to research your faction's advantages, but now I recognise that it is actually well balanced and thought out. That said, I feel the technologies that increase their power should be merged, rather than separate spell and pillar ones. The current situation feels a bit too much research for what you get, especially given how situational many of the spells are. The final, Tier VI technology comes too late to matter in most games, and is the only Tier VI technology that does not provide a Scientific Victory (which seems a silly oversight)
Necrophages - The Cannon Fodder tech is fantastic, arguably a must-have technology for this faction. It is an enabler, however, as their main play-style would not be possible without it. I find Demanding Gods far less appealing, however. It is too situational to bother researching. If it were a trait the faction started with, perhaps I would use it, but as a technology you have to research, there are just better options.
Vaulters - Endless Recycling is fine, for a Scientific Victory where you have large cities, but perhaps a little on the low-end. +2 per lvl2 district is not really a big deal, especially given how many thousands of Science/turn you require for that Victory Condition. An OK tech, but it could be better. The Deep Generator on the other hand is a good technology you can use no matter what your plan. It is not super-powerful, but it is generally useful. Strength of the Vault, however, is fairly useless. More Fortifications does not help when fortifications are essentially meaningless to begin with. If Fortifications were more useful, then this would be an thematically excellent tech.
Wild Walkers - Way of the Woodlands is a useful technology and well worth researching. You would be trying to keep your fragile units in forests as much as possible already, so making that even more beneficial is only good.