I mean, their kits are really similar. Aatrox's W is a terrible version of Xin's W, his E is slightly more useful but much less consistent than Xin's, and his ult is an ok AS boost, but is nowhere near as useful as Xin's. The only thing better in my opinion is his passive, but, again, it's not nearly as consistent.
YumaS2Astral1 votesWell, aside from having a free GA, Aatrox is also manaless. In addition, to knockup an enemy, Xin Zhao must hit that enemy three times, and he can only knockup one enemy. Aatrox, on other hand, can potentially knockup multiple enemies with a basic ability.
Those are all the advantages Aatrox has over Xin, though.
Omnem Occido1 votesRight, but the area in which he can land is small and can be side-stepped. Xin's Q's knockup is more reliable (not to mention, it gives so much more damage and utility, what with the cooldown refresh it gives). Also, while Xin's abilities cost mana, Aatrox's abilities hurt him, for the most part. Xin gets Aatrox's bonus damage for free, and his heal, both being passives with on an ability that gives him really good attack speed.
CerealBoxOfDoom1 votesits just you