[karlosovic]

well Jan-Minsc is a bit funny, and I think Edwin will argue with pretty much everybody.
-I think Aerie and Edwin causes fights (fun, but you could lose one/both of them).
-Jaheira isnt much fun combined with other NPCs, but she probably has the most sub-plot related events of anyone (if you can get her to work, she's also got more bugs than anyone).
-Jan likes playing tricks and making jokes, he's generally good value that way (as well as a great thief and ok mage)
-Most evil characters will cause trouble with the good aligned characters, which can be fun, but also problematic. I would probably recomend taking one of them anyway because it's worth trying for yourself. Just save regularly in case someone gets upset and leaves forever with a bunch of your equipment.

general tip, the best dialogue usually occurs between clashing personalities. Lawful Good + Chaotic Evil = fire works

another thing, I think Anomen and/or Haer Dalis can contest you for romances.