I can't believe how topics like this will attract some serious flames. It's like being near a swamp with a bug zapper. You can just sit back and know some bugs are gonna zoom as fast as they can to their doom.
OT: The only defining factor owning either console is the game lineup. Also consider finances. If you can't afford a PS3, just save, if you are nutz about its lineup. Personally, gimme the 360.