Make Fizz's spells play distinct roles from each other
Something like, making Q the aggressive mobility/chasing spell by giving it a very low cooldown with lower damage, the W gets the damage spell which he needs to max first to deal the most damage and E gets the utility spell. In other words: Take damage off from E and put it onto W. Then Fizz can adapt to his needs and choose the best skillpath. Currently he can max E and get a slowing, high damaging, insanely high utility spell on a low CD.