But for me GTA IV would be one of them!
I agree with the COD thing, since they seem to be in a rut of churning the same shit out every time now, but GTA IV was an accomplishment. It took the bar off the map in terms of what's possible. Sure the missions were all the same:
Drive here, shoot him,
Drive there, shoot him,
Ooh look a motorcycle!
But it deserves its 10/10 more than any other game ever made. They created a living city on a console. Everytime you play it you'll find something you haven't seen/heard.