It is an interesting trade off. Public corps make more money, from both monthly upkeep, and initial selloff, but you don't get control of them.
CEO corps are useful if you want to use back to work schools and special clinics. They are the best option I see for most presidents, given how much money they make.
State corps are basically tradeoff against public corps really. You don't get initial profits from shares, but you get much more of a say with what you can do, such as profit transfer, sending off money to keep it floating, etc.
As for whether or not the fee is too high, I think blueserpent is right. If we remove or even lower it, it only gives more incentive to rise taxes.
Either way, I don't mind, I run mostly state own corps. Communist dictator!