Juma, just a correction, Mass Effect is NOT more popular than God of War or Uncharted (and since we're talking about 360 appeal, PC sales wouldn't count). Fable isn't either. Only Halo and Gears count.
I'd say, the sole driver is XBL, honestly. Halo and to an extent Gears, coupled with the overall library and more recently Kinect, are further X360 pushers.
But why it sells more than PS3, it's a dead horse, but just to end it already:
- Headstart, and cheaper price.
- Sony tarnished their overall brand in the US, and really bad.
Rockstar: Announce Bully 2 already and make gamers proud!
Kojima: Come out with Project S already!