I like Lord Fear because of the humour. He was also played extremely well. It's plainly obvious that Mark Knight enjoyed every minute of it!

Sylvester Hands is a marvellous character too, imo. Sort of an utterly inept and dozy Fagin. Every scene with him and Lord Fear was always funny.
I've always quite liked Hordriss, too (incidentally, when choosing my forum moniker I wanted to select one that would best sum up my incessent intellectualism and penchance for pompous posturing

I like Motley, too, if only because of his longevity. I think a Km dungeon is never complete without a jester.
I've never really hated any of the characters. Some of them I really like (Treguard, of course, goes without saying). The rest I've never minded.