Best RPG in general is a bit of a lot. Maybe best single player open world medieval fantasy RPG.
As for best RPG in general, I don't know if it beats out Mass Effect 2, Xenoblade Chronicles or Dark Souls. But those are older and get a bit of added credit for having survived the test of time imo. We'll have to wait n see how Witcher 3 is regarded in a few years. Skyrim, for example, seemed to lose a bit of the acclaim over time. (although is still a brilliant game)







