Egh, I feel that the majority of ADC's are balanced.
Some exceptions. Draven is a bitch, you fear of doing anything wrong cause if you do BOOM lane lost, early-mid-game lost, GG.
Vayne is another one of those.
I just tried out vayne. I don't even play her. I played her jungle.
The sheer amount of damage and sustain she has is !@#$ insane.
I was behind by 4 kills, and 60 CS. (compared to the rest of my team average.) The weakest enemy had 5 more kills than me.
I went 1 v 3 and won, their ADC, their support, and their Tank.
Honestly WTF her damage is INSAAAAAAAAAAAANE.
Counterplay? WHAT counterplay? She just SHOOTS you. Stun + 3AA = kill.
Jinx, however, can be countered. The key here is that she doesn't have the same level of sustain, since she had to focus AD, while Vayne goes AS and kills people......
EX: Vayne gets 2+ lifesteal items. Jinx gets 1 usually.
I find jinxes , even late game, fine enough to kill as long as you get to her. Remember, her CC isn't that good.
I feel that Jinx late game isn't that good...typically just tower-busting. Trist , to me at least, falls off late-game as well.
I dunno, just get close to them and they're dead. Caitlyn still pretty much counters them, assuming equal peel, Caitlyn can outkite them (sort-of) and about 1-shot them with her Ult XD
ADC's are fine-ish now. IT's junglers that need the real rework.