ATTACK DAMAGE CARRY...

Urgot.

the best adc in the game i think is fiora

THEY ARE CALLED MARKSMEN CPT CAPSLOCK

Quinn anyone?

Always depends on the team, but the most versatile and one of the highest damage capacity marksman is Jinx by and far.

Why do so many players ask this Question, all Adc can be played well it depends on your counterparts (Enemy Team), Support, and your play style.

Due to her interesting and flexible build a well played Janna is a very powerful, though rarely used, adc. Utilizing her storm shield for extra damage and using her wind attack and slow to ensure that you hit make her very powerful

It depends on who your looking for. If i was to give you one I'd pick Draven, Jinx, Sivir, Vayne, Ezreal since I main them but not sivir lololol. I've played Urgot before and hes pretty op if you hit your poison and no one barely plays him no these days.(havent seen a Urgot player for a long time so yeahh) You should just pick someone that you really like for an adc champ so you master them and then counter other adcs hope my advice was somewhat helpful :P