Interesting there's no love for Diablo, which was considered a RPG when it came out.
Neverwinter Nights - has this even been mentioned?
Both of these would be in my top 5. NWN more for the expansions & user-made content than for the campaign that shipped with the original game. I always forget Diablo II when the favorite RPG discussion comes up. Since it leans more towards the 'action' end of the 'action-RPG', I tend to categorize it that way.