Driders…. Always driders.
Oh, another tough one. It’s a toss-up between beholders and illithid. They are both a lot of fun from a game stand point. And by fun I mean “AH! AH! AH! AH! RUN! RUN! RUN! RUN!”. Seriously though, one of the most fun adventures we have run was the Illithiad modules.
Bodaks. When one of my characters died by a bodak’s gaze and then turned into a PC bodak for a time, it was a lot of fun. Short lived, but fun. Unfortunately, as an undead, there was no way for the party to heal my wounds and eventually the damage accrued to the point of my destruction.
As a player, I think my favorite NPCs would be a tossup between Lord Soth from Ravenloft and all the various beings who believed they were Keraptis in White Plume Mountain.
What’s the best way to put this? I HATE TRAPS AND PUZZLES! There, I said it and I won’t take it back. There is not one single, solitary trap or puzzle I’ve enjoyed or liked as a player. None, whatsoever. Whenever I encounter a trap or puzzle as a PC, I let the other PCs take care of it if possible and will only involve myself if I have to. Even when I play a rogue, I’ll let the others deal with puzzles and I’ll take traps.