Top: when going yorick, I hate playing against fiora. she outdamages you early, and since your only real "escape" tool is a wall she can dash past before it pops up, once she's on you you can't escape at all.
Mid: Yasuo. Not so much not being able to fight him (I can do well as ori), just that he's so obnoxious to fight. I feel like his passive should just give damage reduction instead of negating, say, someone's ULT and then getting a shield.
Jungle: Master Yi. He builds up so much movespeed and has 3 blinks, it's almost impossible to target him.
ADC: Caitlyn, I guess? I don't really have one here.
Supp: Thresh and Blitzcrank. TOGETHER. Worst game of my life was where the bot lane was a thresh and a blitz who built full damage, threw hooks everywhere, and would blow you up.