Hmm, it's a tricky question. One possible (fairly arbitrary) way of looking at it, is considering the genres of the 10 best selling games
360
5 shooters
1 racer
1 sandbox
1 action adventure
1 rhythm
1 platformer? (bundled)
PS3
5 shooters (including MGS4 as a shooter)
2 racers
1 sandbox
1 action adventure
1 platformer
Oh bollocks, I genuinely thought that was going to turn out differently :P Ahh well, posting anyway