You have to nerf fleet footwork + overhead, fix adc itemization, and rework enchanter supports.
Fleet footwork allows crit adcs to have an extremely easy laning phase as they can heal all poke and can get out of all ins with the move speed buff. This combined with overhead allows them to not be able to get pushed out of lane while eventually pushing mages out of lane unless they also take fleet footwork.
Second, adc itemization is way cheaper compared to ap itemization. This means an adc with equal farm to an apc will be always ahead in items. Meaning the ap has to win lane to compete, however, this is almost impossible thanks to fleet footwork.
Lastly, enchanter supports are so biased towards adcs as their buffs benefit them far more. This causes the adc to get much more powerful while an ap only gets little benefit.
I hope to see some changes in 8.10.