Well I've decided to make a project out of comparing three or four currently available fantasy role playing rule sets that I know well. These are D&D 3.5, Castles & Crusades, and Warhammer FRP. Though I am tempted to include Conan RPG as an alternative to the D&D tropes using the D20 ruleset.
I'll take step by step through comparison of character generation, advancement, combat and magic. Setting isn't really something that I can compare as only Warhammer and Conan have a default setting assumed, though it can be argued that all D&D is based around the Greyhawk world.