I think that it is hard to say. On one hand, GTAIV came out before the PS3 really hit its stride, as well as having Microsoft timed-exclusivity with some of its content. On the other hand, despite those advantages, total lifetime sales are actually rather close. I do think that the 360 version will still have an early lead, due to the series's popularity in America, but lifetime-wise, I can see it being very close.