I'm going with Warhawk:
- huge, detailed, and well thoughout maps with many smaller "portion" variations
- ability to serve your own games (ranked or unranked) with parameters you specify (also handy when the official servers are down: there's usually still more than 130 servers to choose from in that case)
- 32 player games (!)
- Air and ground combat
- excellent balance of air and ground vehicles and the various weapons
- ability to carry nine different weapons simultaneously (soldier: 8 primary + frag grenades, airplane: 8 primary + machine gun)
- Extensive dev support/new content after launch
Not trying to be a fanboy. Of course, it's hard when you own the best console eve... dang it