Xbox 360 is heads and shoulders above the PS3 right now for sports games. The frame-rate for the most recent Madden was 30 fps for PS3 while it was 60 fps for 360. Developers just haven't quite perfected the reportedly finicky PS3 programming code.
Things will probably even up quite a bit over the next couple "generations" of PS3 sports games.
I'd have to give the nod to 360 as well right now in terms of online play.