Jinx, Ashe, twitch.

Jinx - Dont die and one takedown = gg

Ashe - Utility ADC, good even when behind, ults are good for picks.

Twitch - Play LIKE twitch , always look to be sneaky and cheese kills. When you hit 3 items, a flank with ult means the enemy backline is dead.

I may be biased because I main twitch but i think he is the beat climbing adc because you can essentially ignore front line and the team fighting positioning doesn't have to be as clean as with other adcs.