Best graphic QUALITY? That would be Crysis 2 with MalDoH 4.0
Battlefield 3 isn't even close.
The Witcher 2 isn't close (don't confuse art direction here with graphic quality though......The Witcher 2 excels here. It is a tremendously beautiful and artistic game with the best graphics in any RPG to date).
The only thing I've seen that can compare with Crysis 2 / MalDoH is Metro2033. Fantastic lighting and texture quality in that game.
The original Crysis still deserves mention here. People are still creating environments in CryEngine2 that are incredibly good......the engine is capable and the outdoor lighting is a large part of what makes it so good.
http://earthmachine.home.mchsi.com/desertcry.jpg