I was fascinated by the Meta-Story of Might & Magic 3, 4 and 5: Xeen, Clouds of Xeen and Dark Side of Xeen. Of course the game was pure running around from fountain to fountain and fighting, sleeping, fighting, etc.
The Ultima Series were amazing. Simply.
But my all time favorite RPG, maybe because it was the first I ever played was "Legend of Fairghale" on the ATARI.
Closely followed by Ultima Underworld. The 2nd part was a bit overdone.