Good point - so I should get the 360 version. I can't help feel the PS3 version should be better, but my PS3 controllers are the lifeless hamster version
If CoD4 is anything to go by then the two versions will be indistinguishable from one another. I would err on the side of XBox if you're only getting it on one, because the online play is slightly less likely to crap out than on PSN.