Pokemon has ruled handhelds since the late 90's. Now with the release of Pokemon X & Y, I think it'll reach a popularity that hasn't been seen since the original Red/Blue/Green days, but it'll never be that same type of phenomenon again.

Mario has ruled Nintendo consoles but many are saying that it's prowess as a system seller has waned recently, but we'll see how true that statement is once SM3DW and Mario Kart 8 are released. I think if anything, people were fatigued by the lack of innovation in the sequels to the NSMB series.

Halo sold Xbox, Xbox 360 and it'll sure enough be the seller of Xbox Ones.

Grand Theft Auto sells itself.

It'd be nice if Sony had one or 2 franchises that had the same kind of long lasting appeal, but I can't deny how amazing they're exclusives are.

EDIT: Itd be fun to see the big three collaborate on game involving all of their signiture characters.

Sony has Gran Turismo.

Any game people actually bought the system for, not the game people bought for a controller...