[Dirty Meg]

Before you ask, yes I have to much time on my hands.
From best to worst.

1. Keldorn. One of the best fighters in the game and has some of the most useful abilities (dispel magic, true sight, immune to charm and confusion). Needs gauntlets of dexterity to be good tank, but who else are you going to give them to?
2. Korgan. The best fighter in the game. Unfortunately, pure fighters are as dull as Birmingham. Occasional funny dialogue.
3. Aerie. Bit of a liability at low levels. Godhead once SoA exp cap topped. Romance quest that works. Likeable character.
4. Minsc. Great fighter, Great dialogue. Slightly useful abilities.
5. Viconia. Best cleric. Can fight a bit if suitabley equiped.
6. Imoen. Good mage, can handle all your thieving needs.
7. Edwin. Damn good mage. Also a lady-boy.
8. Jan. Only NPC thief who can gain levels throughout the game. Also hilarious.
9. Mazzy. Useful all round character. Also, least annoying personality.
10. Valygar. Reasonably good ranger. Can backstab.
11. Cernd. In werewolf form excellent fighter at low levels. Also fun to use.
12. Anomen. Ok all round character. Boring to play. Most annoying NPC. Only romanceable male NPC. I'd rather romance Boo.
13. Jaheria. The most boring character in the game. Good for subquests though.
14. Yoshimo. Good thief but you can't keep him.
15. HaerDalis. Jack of all trades, master of annoying the hell out of me.
16. Nalia. Has no advantages over Imoen as a mage, and is a much worse thief.