Halo would sell much more. If you look at past sales, yes gran turismo has sold more, but they also sold more on a much larger user base than halo. the percentage of xbox owners that owned halo is an incredible accomplishment. I think Halo is a stronger brand with much more appeal, but then again, I'm American, so what do I know:)
@bouzane
Your MGS4 example is pretty unfair. the ps3 game library isn't nearly as saturated as the ps2's library was at the time of it's release. Also, that game was bundled with hardware, and it got way better review scores than MGS3. MGS3 was also very underhyped in comparison. User base does make a big difference as far as sale figures, which is why so many games are multiplatform now SO THAT THEY CAN MAXIMIZE THE USER BASE. It seems like a pretty logical point to me.
