Aatrox is always a good pick into most Champions if you know how to play you will win it most of the time. There are almost no bad matchups for Aatrox most of them are Skill-Matchups.

How can you tell the difference between a GOOD Aatrox and a BAD Aatrox? Well, What do you build into champion XYZ? How do you use your Abilities? Do you play around your CD?

Also, one great thing about Aatrox is you can play him Aggressive and Defensive. So it doesn't matter what kind of player you are. He will please you either way once you mastered him trust me.

Laning phase. As I said Aatrox can be played aggressive and defensive.
If you're playing defensive: You want to slow push, set up freezes, and fight in your wave like a smart player.

If you're playing aggressively: you perma shove the wave, poke the hell out of the enemy under their tower ONLY if you know that the enemy jungle isn't nearby.

How do you wanna trade on Aatrox you need to learn how to space on him. Also, you need to learn the Cooldowns on Aatrox really important you don't wanna stand nearby an Enemy Darius without any CD on ur Q, W or E you would die instantly. (It's just an example)

Mid game: Rotate to objectives and team fight for late drakes and early Heralds. Other than that you want to keep the pressure so your team has an easier time dealing with the enemy team. But overall it's up to you how you want to play. You can also peel for your ADC or Midlaner if they are really fed.

Late game: Unfortunately Aatrox gets outscaled by most champs. You need to step up your game if you reached the late game because it will get really exhausting for you. Basically, you have to team fight a little bit more and you will punish the enemy if they miss/overstep. What you can also do is catch the enemy team off guard. e.g Enemy Jungler/Adc wants the Red/Blue buff.

For max Q range you should E Dash and Flash instantly right before Q ends [Q->E,Flash]

Basic Aatrox combo (GORE VERSION): Q1 -> W -> Q2 -> AA -> Gore -> Q3
Basic Aatrox combo (STRIDE VERSION): Q1 -> W -> Stride -> Q2 -> Q3 -> AA

For max W range you should E Dash first and then W [E->W] you can combine it with Flash as well but you really don't want to waste your Flash but for the style points I list it for you [E, Flash -> W]