The only way I can think of to have perfect balance is to take every set and line them up side by side T 1-9 and standardize everything about that tier from accuracy, endurance, damage, recharge and animation time. This would basically make every power tier the same with different flavors of damage which would probably invalidate the balance.
Then for those ATs like controllers, start making trade offs to add the needed controls. Since you would be adjusting the damage to add the controls, you would have to move that damage to another power.
That way if every power was activated they would end up doing the same damage in the same length of time for every AT.
You would be rewriting most of the game.
See everyone in CoH 2!