valdaintheking: It remains to be said. Enlighten me...
Depends what are the things you are looking for the most in an RPG. Some are looking for a story, some for exploration, some for challenge (in combat) and the stats (development of your character/party) etc.
Since to me the stats part seems to be pretty important, I've lately found e.g. Icewind Dale quite satisfying, playing it on the hardest difficulty level. I just love that sound of a party member levelling up, learning a new kickass spell, or finding some weapon or item that gives me some much needed abilities, like running faster or regenerating health (haven't found yet in IWD, unfortunately). And then being able to kick the ass of that big bad dragon that easily brushed me off earlier.
I like the exploration part as well (depending on the RPG), and the story. The story is pretty generic in IWD (finding who is causing all the trouble to a nice village), but keeps me still entertained. To me a good story in a game is like good in-game music: always nice to have and can make the gaming experience more pleasant, but still not necessarily needed in order to enjoy the game. I actually dislike many JRPGs which IMHO concentrate too much on the story and character interactions.
I won't say what is the best RPG, as there are still so many big holes, like only barely playing the TES games, still to properly play many Bioware/Interplay RPGs etc.
RaggieRags: I would say that's Baldur's Gate 2, modded. Replaying it now is almost depressing because it makes you realize how much worse Bioware has gotten.
Wasn't e.g. Dragon Age Origins supposed to be pretty good too? Or are you referring to Mass Effect 3 or something?