While I think that both Sony and Microsoft can go do some graphically explicit things to themselves, so far the 360 has had a stronger title release for exclusive games. This may change in the next few years, however that's a crap shoot at best.
I am angry at M$ though because my Elite 360 just RROD'd, and at the beginning of the most tilte rich review period I could ever imagine (Gears of War 2, Mirrors Edge, Prince of Persia, Fallout 3), so that taints my opinion a bit. It basically comes down to personal preferences. While yes many 360 games have gone to PC (and even PS3), with the PC versions quite a few have DRM imbedded on them, so the choice is yours.