Riven "Balance"
Personally, I don't have much of a problem with the champion on anyone outside of if I pick someone so ridiculously squishy top I deserve to lose, but.
If a nerf is -ABSOLUTELY- needed, as everyone seems to complain about. (Don't get me wrong, I hate how brainless she is.)
Why don't you just reduce the time she has in-between her Q? So she actually has to make decision making between whether she wants to escape or all-in something. Instead of giving her... Like 6 seconds? To basically bully the lane just by having a buff.