I find the xbox far more online multiplayer oritentated. Ps3 didn't even come with a headset!
I've played great games on both consoles, but i think the xbox cynches it enjoyment wise as friends and family are on the xbox and for me it's all about the banter while playing.
If you ask people what great games they played when growing up you always hear about goldeneye sessions with mates or mario kart or whichever football game or halo lan matches etc.
It's the social aspect for most that makes it enjoyable, so find out which consoles your mates have and go with that one. It'll be far more important than exclusives or controller shape etc.