Well, as a totally non biased decision, Get the 360. The new Kinect is out, with controller-free games, as well as a large variety of other games, from Forza 3 to Left 4 Dead 2. Also, I don't know if the PS3 can get games, content and other stuff from a shop like the 360 can, so someone correct me on this. IT may not have the best hardware vs the Ps3, and you have to pay for on line, and other stuff, but it is overall a good console.
Alternatively, get whatever your friends IRL play.