Regardless of what ADC you pick she's going to out heal you, out damage you and outrange you. You might as well just pick a mage or a wave clear machine, if she plays the lane properly you're not going to gain any territory on her and just get permanently dove under your Tower.
I'll take Miss Fortune or Aphelios.
Cait is so stupidly strong right now but riot prolly gonna nerf her ult cd only. They have a history of horrible nerf decisions. Essentially what needs ti be done is they need to remove her Passive all together and rework it into a new one as well as buff her W for compensation. I made a post where I thought up some stuff for her:
New Passive: Cait gains movement speed toward CC’d champions. This would include champions who are trapped by her W. New W: Her traps remain permanently for 5 minutes. Can not be targeted. She can have more than 5 on the map. When activated, the enemy takes damage and additionally takes additional damage from Caitlyn when auto attacked.
I feel as though these would work hand in hand very well and still make her kit cohesive.
1 nerf I’d also give her... her Ult can no longer freaking reset if an enemy zhonyas/dies/or ect. -.- stupid passive affect to have for someone who can essentially already just chase you down with huge range.
Both can force an all-in which is what cait struggles against, can farm without taking too much harass.
