what's wrong with locking a mage top?
I'v played Ahri top.
and she makes people go POP!
Yes yes YES!

I go kass top and its much better than mid. Yeah there aren't alot of ap champs for kass to make his q worthy as much. But the main thing is kass doesn't get poked to hell top lane. Which makes all the difference.
Hey, don't worry, I completely understand you. You have to pick someone unconventional just to counter them, your team often is left with no tank, otherwise they just poke you to death and punish your lack of range.