Well ever since the release of the reworked Warwick, there is now literally no reason to pick Aatrox. As bad as Aatrox is, he is supposed to be a sustained fighter but in order to build decent sustain, you have to build damage so your heal can be worth something. Building rageblade is essential in order for him to be at all relevant.
Now? Warwick is better than Aatrox in quite literally, every way that it is laughable to compare the two. Lets just compare the two's sustain.
WARWICK
Warwick's basic attacks deal 10 - 44 (based on level) bonus magic damage on-hit.
While below 50% maximum health, Warwick's basic attacks also heal him for the same amount, with the healing tripled to 30 - 132 (based on level) while below 25% maximum health.
So in other words, below 50%, WW heals 10 - 44 flat per auto. Below 25%, the heal is tripled. That is per auto. Thats not even assuming if he has Rageblade which will double his healing potential. Thats not even including the immense damage AND heal from his Bite.
AATROX
BLOOD THIRST: Aatrox heals himself on-hit every 3rd auto. While Aatrox is below 50% maximum health, heal is tripled.
「 HEAL: 20 / 25 / 30 / 35 / 40 (+ 25% bonus AD) 」
Lets even assume Aatrox has 100 bonus AD and it's maxed rank. He heals for 115 below 50% EVERY 3RD AUTO.
This means that Warwick can outheal Aatrox immensely despite not building any damage. Aatrox is now literally useless. Xin is a better sustained fighter with the buff to his crit, and now Warwick.
They couldnt even bother to make Aatrox untargetable while in midair on his Q. Everything about him is counter productive.