In my opinion, when there is more than one shareholder, compensation needs to be discussed and agreed upon by all (in many cases, ideally at the START of the year).

Increasing the compensation of one shareholder DECREASES the pass-through income (and therefore eligible distributions) of ALL the shareholders.  Unless compensation is agreed upon by all shareholders, arbitrarily increasing wages of one shareholder is effectively stealing income from the others.

If they can't agree, they shouldn't be in business with each other.

There aren't a lot of variable besides the amount of compensation.  Offhand, Section 179 and accelerated depreciation versus not-so-accelerated depreciation is the only thing that I can think of, although very likely there are more things that I'm not thinking of.  For things like depreciation, I would ask if there is an Operating Agreement that shows how the corporation should handle if.  If there isn't an Operating Agreement, I would just do what is best of the shareholder that I am working with.