My favorite companion is Kan Po! Witchdoctors get him at the beginning of the game, and I always love him in the battle. He's been my firstmate on most of my battles,ever since I started leveling my Witchdoctor. He gets better and better once you level/ promote him.
Well, I'm not too far into the game, but so far, I really like the Mustang Toreador. I can't wait to promote him and see how much better he gets!
~Sly Wolf Laveer, Level 31, Swashbuckler.
He doesn't get much better which is a shame, he gets one epic talent and you can choose to get critical strike instead. I really wanted more from the side quest companions because normally they are the ones that look the coolest but there promotions suck and they can't compare with the main quest companions.