Ahri's current state
Despite being a mage, Ahri is not doing well. Not at all. There have been times when she was strong or weak, but right now she's just terrible. Before I get downoted to oblivion, hear me out: I don't think mages are fair to play against. As an Ahri main, I hate them too. They do everything too well for too little. Anyway, back to my main point.
When the tower plating mechanic was first introduced into to the game, Ahri was doing pretty well. She could shove the wave in and get a lot of gold from turrets. Pushing was always her strongest point. She has no real damage, only survivabilty which is, well.. only really useful in lower elos. As platings were nerfed more and more, Ahri gradually got worse as well. At first, plates gave a little less gold, which was, well, tolerable. But then they were made so strong that unless you are playing against an afk you won't ever get past the second or third plate.
In lane, she barely has a little kill pressure if any. She can't oneshot even with ult and ignite, not to mention that you have to pick Glacial Augment to actually feel the tiniest bit of usefullness(not that she can kill people with electrocute). Even if you get super far ahead, you can still just barely oneshot a few squishies. A 6/0 Ahri won't carry a game, while a 2/0 Yasuo pretty much kills everyone. Same for pretty much any mage.
Her ult's cd is absolutely ridiculous compared to, say, Diana: Ahri's lv.1 ult cd is 130 sec, while Diana's is 100 seconds. And I don't think I need to tell you which one is more useful.
Her winrate is pretty high, up until she gets into higher ranked games. She's absolute garbage as a champion and can't compete with ANY midlaner you can think of. You could imagine her playing against any midlaners, and she won't win. She can't.
It's not just me, either. You could ask any Ahri main in higher elos or any pro, and they will most definitely say that she's weak. She has been for a while now. Send help please.
and three or more level advantage youre the one with a problem.
Ahri is comparable in damage to most mages. Most mages however do not have the mobility or safety that Ahri does. As for Yasuo... You cant really compare Yasuo to an assassin. Hes a hypercarry, youre not.
Are absolute garbage champions because of riots constant nerfs and community whining. THOSE are champions who cant compete in solo queue, Ahri is a champion who may not be in the limelight but is never weak either. Quinn is another such champion who isnt really ever weak, but also isnt ever in the limelight.