Don't really care what it is, but the game just needs one, maybe two more classes. We pick 3 of 6 as it is, and half the characters I make end up with the third class just being left blank or really only using it for one passive.
An interesting issue with there only being the 6 classes is that a lot of people end up with the same overall build despite the class mixing.

I suppose adding an extra active skill to each existing class might help instead, and that'd probably take less effort.