Mordekaiser.
It only seems to get picked when I've already picked my top laner as a melee champion (mostly J4) and I just get destroyed. And yet the whole game I know if I had picked Quinn (which I normally do when picking blind, but often switch to J4 if the team has no tanks, or he would synergize well with allied picks, or I thought a different opponent was going top) I would be absolutely shitting on him.
Basically, he's the new Darius to me. I used to hate top lane exclusively because every time I played I would try to pick a melee tank and they would always pick Darius and I didn't know what to do and got stomped. Now I can handle most Darius' (even as melee), but I can't do anything to a Morde.