360 has great library of games as does PS3.
There are advantages to both systems. Plus I never been a one system lover.
360 has Gears of War, *****, Halo, Crackdown, Dead Rising, Fable, Dead or Alive, and others I cannot think of. Downside is the pay to play online. But that is where the...
PS3 comes in. PS3 has Ape Escape, Metal Gear Solid, God of War, Gran Turismo, Little Big Planet, Infamous, SOCOM, Resistance, and Uncharted.
Not to mention all the multi-platform games. If you want online with one game get it on PS3, if you want a game to just play go with preference, and simply enjoy your video games.