Note: Umbraco has discontinued Umbraco 5 citing it was too slow and complicated.
Although I prefer Orchard CMS, I've been spending a great deal of time learning Umbraco and recently Drupal. Umbraco v5 is a CMS based on ASP.NET MVC just like Orchard whereas Drupal is based on PHP. However, as I mentioned after reading Using Drupal, Orchard CMS was inspired by Drupal so it is pretty eay to...