I always find threads like this interesting, because they tend to show the full range of reactions npcs provoke, and the different experiences and expectations people have.
Personally, a lot of the characters accused of being 'irritating' in this thread were some of my favourite npcs, because they tended to bring the party to life. When I think of my favourite pcRPG characters, I immediately think of people like Aerie, Nalia, Anomen, Xan, Bastila, Mission, even Alistair (who I regard as one of the saving graces of an otherwise profoundly mediocre game).
Frankly, and I know I'm opening the floodgates for a torrent of abuse here, the only active npcs I can think of who made games unpleasant for me (which is different than disliking their personality but finding it immersive - ie, Kreia) were Morte and Nordom, who to me spent far too much of the game seemingly mocking me for playing it (passively in Nordom's case).
I think that if this thread shows anything, it's that it's worth generally creating npcs who fill similar roles, but offer different personalities. I'm sure, as others have said, that Josh et al can do rather better than airlift characters from other games, but as an example if the cleric resembles Aerie then make the Druid resemble HK. At least that way people can have a viable choice as to the personality of their party dependant upon their personal tastes.
...or, of course, don't, and I will love P:E forever for making a game where I struggled with a sub-optimal party to keep around characters I liked. Alas I think I'd be in the minority enjoying that.
Anyway, to get back to the core of the matter, I disliked Morte and Nordom, so flame away.