It's all about the games. If you have a decent gaming PC and use it often, then the PS3 will definitely have more to offer. If not then you'll just have to compare the exclusive titles for each platform and decide which ones interest you more.
The 360's exclusive title lineup for this year seems pretty weak unfortunately, nothing much other than kinect stuff, Gears and Forza.
~ PSN - Trent_Steele ~ Steam
~ Battle.net - Chief#6843