Xbox 360 all the way! PS3 is really nice too from what I've seen, but most of my friends have a 360 and you cannot beat their online game play, in my opinion. I just finished the Fable 3 storyline, but I'm currently working on getting all the achievements. After that I will replay Oblivion, because I lost my saved games and didn't finish the storyline. For Christmas I'm getting Skyrim.
I think I know why I like PS3 over 360. I don't use my PS3 for online gaming. If I'm gaming online, then I'm playing a PC game. If I'm playing to kill time after work, then I'm playing a pure console game without web access. Since my consoles are used just for the games, I guess PS2/PS3 is my favorite based on the games released for the system.
I wonder if 360 would have won against PS3 if I did use my console to play with other people. I only know that PS3 releases better games for my taste than other systems. I also hate the Wii controller. It has a huge learning curve if you don't have a naturally steady hand.