Aatrox might need a buff, maybe AD ratio on ult
I'm not an Aatrox expert, but I once asked on the forums "should I buy aatrox" and the common answer is that he's a little UP right now. His popularity is at around 2 percent and his winrate is below 50% as well.
People suggest many things, like adding an AOE fear, but I don't think that's necessary. Honestly, in my opinion I don't think it's a good idea for a melee champion to be fearing enemies away when you want them to be in range so you can attack them.
I think that a good buff for Aatrox is adding a AD ratio to the ult though. Maybe like 80% AP + 80% AD or something like that. I think that that will go a long way in helping Aatrox be less UP and more balanced. Maybe taking 2 seconds off the cooldown of Q helps too.
One argument against buffing Aatrox is that many think he's a noob stomper like Yi, but I don't think so. I am in bronze, and the average KDA of teammates and enemies I've had who play Aatrox is about 6-8-7 whereas for Yi it's more like 11-6-4. Especially with Aatrox's high skill cap I doubt he's a "noobstomper"