I've played on both systems. I just own a PS3 since it has a Blu-Ray player, otherwise I'd have a 360.
I've probably got 24 hours or so split screening on the 360 with MW3 and BO2. What I've noticed is the PS3 has less 'trickshotting snipers' and 'squeakers'. By less I mean 10x's as less from my experiences.
I only did slightly worse on the 360 than I do on the PS3 since I don't really use a 360 controller all that often. The quality of the players honestly seems pretty equal to me.
The PS3 community mostly seems to be the 'older' crowd.