You're in the Xbox forum so the opinion here is going to be a little bias,
Xbox benefits:
Cheaper
Kinect is awesome
Exclusives like Halo, Forza, Fable
Smoother dashboard and controls
Most reliable online service
Future longevity
Playstation benefit:
Games usually release with higher graphic compatibility
Exclusives like naughty dog games and MLB the show
Cheaper online service
Both have their downfalls of course, but I think playstation has more of them.