A thought on ADCs
I don't play ADC, but I was thinking about why they lack real influence in the game these days and I've come to the conclusion that they can be improved by giving them an elevated (compared to other roles) base movement speed.
For one thing, they're archers, not siege tanks. And I'm aware the game doesn't need to take reality into account, but I wanted to say that. Secondly, they really should be refocused in the existing meta as (literal definition here) skirmishers an not duelists. It makes more sense for them to be mobile darting in and out of the minions and support set ups than it does for them to just stand there. Third, I think this leaves them vulnerable to their current counters (assassins) while giving them more outplay against things like Juggernaughts and mages (in the former to kite, in the latter to escape.)
tl;dr - ADCs haven't evolved much coming out of the old "KDA rules" LoL into the new "push those objectives" meta. You notice this in their lack of subclasses, even though there should be a few. (Siegers, pokers, and Heavy Hitters)