I like the Xbox cause of the games, yes, most games that are on the 360 are also on the PS3, but with the Xbox, you get Halo, that was the selling point for me. I bought an Xbox Original in like 2005 or something, for Halo 2, then upgraded to the 360 in 2006 for Halo 3 and other games.
Majority of my LANs have Xbox 360 Gamers, I advertise them as Console LANs and we haven't seen a PS3 show up.
Personal preference, really.