Neither actually...I typically buy all systems in any given generation, it's just the order that differs. This gen the 360 was out and had Gears coming, so I picked it up first. 3 years later it's managed to keep me quite entertained so I haven't felt the need to pick up a PS3 or Wii (yet!!). I am sure, I will eventually though.
Rare being on the 360 was the proverbial icing on the cake (so to speak).