If you care about cross-platform play, get an an eightarc, as a few people have already recommended. Otherwise, get this as a starter kit. If you are out of mind or just prefer keyboard controls, get a HitBox (PS3/PC only for now, though).
PS3 version because of the pressure based controls
Sounds like a pedantic difference, but this matters quite a bit. I think the pressure-sensitive stuff is assigned to the d-pad on the 360, but I could be wrong. Either way, it would make some of the more intricate CQC stuff a bit of a hassle on 360.