Canderous was a quality character, if sometimes a bit too evil (me bieng a traditional LSer and all).
He'd still get my vote though. I liked Mission a fair bit too. Nither Mission nor Canderous appeared in my party often, I just took Force users with me. However, I found the dialogue and personalities associated with the Jedi members of your team a little to cliché-d, you had your bog standard love interest and old man. Carth seemed a little too pathetic as well, and HK was just too evil to the point of bieng slightly pathetic IMO.
Juhani, Canderous and Mission were the only party members who brought anything new or interesting to the game in my opinion, and it's a tie between the three of them for me.