I got them both and the 360 is used to play games while the PS3 is used for mostly movies. The reason why I play games on the 360 is because first they have much more great games and second live is better than PSN and third I like the achievements on the 360.
My favorite games for this gen:
1. Gears of War 2. MGS4 3. Killzone 2 4. Halo 3(Underated by many) 5. Mass Effect