I have tried to stop using Quinn over and over, but I always come to the same conclusion, I might like the other companions more but I can kill more, faster with Quinn than any other combo over the long-haul. It seems like with anyone else it is faster on most fights, but I have to regen after every fight and I sometimes struggle on a bad pull or against a higher level baddy. With Quinn some fights are slower but you don't really have to worry if you pull two groups or even three sometimes, also after the easy fights you don't have to regen at all just run right in again.