Need advice on new class

[CFM]

No matter what classes you have, a 6-character party will beat the game no-problem.

However, you mentioned inter-party banter being important. I should point out that there are pairs of NPC's that provide more banters when both are present in the party at the same time, than they normally would if they were in a full party without their "other half". Some examples:

Aerie and Haer'Dalis (especially if you try to romance Aerie)
Anomen and Keldorn/Aerie (during Anomen's issues)
Mazzy and Korgan

Probably a few others...

[dragon wench]

If you like banter, I can't recommend Jan Jansen highly enough.
One of the most entertaining and chatty groups I ever had was:
Jan Jansen
Mazzy
Korgan
Minsc
Edwin (happy patch so I could use him with Minsc)