I'm only asking because for Christmas, my mom got me this version (she told me because she wasn't sure what I wanted), and I wouldn't buy it otherwise (lots of other games to play.) But I can get it returned for the 360 version if I want.
I have both versions and find myself playing the Wii U version more often. The reason for that is I can play on the gamepad while my TV is occupied by the family.
The small community does have an impact on the playlists. If you are looking for objective based modes outside of domination you'll be out of luck. If however you are a TDM player you'll have plenty of people to play with.
having the flexibility of playing the game just on the gamepad is huge.... use it all the time! The game plays very smoothly on the wii u, we have the choice of motion controls as well. only downside is number of players on-line.... but that should pick up over the next few weeks!