If Gears & Halo 3 Are The Killer Games On 360 Which Ones Define PS3?

[Jagg-off]

When I think of the PS3 and games, I think MGS4 and LBP. But I don't own a PS3 and I suspect that PS3 owners will be able to spit a few more out. I also think that a lot of people's answer will be based on sales.