Well... In my opinion literally every class is in need of fix in one way or another, but I'll mention Aisha as I'm most familiar with her.
Base is... Well basic, however she needs some command fixes, especially her Z and X cuz they are pure shittu. Skills... Well, I wouldn't be mad if they revamped some animations or even changed some skills. And remove Memorize... Or give it to AeS path cause she can benefit from it at least and make the other two classes have their own little systems to be fair with 'em.
Metamorphy should be more Dimension, more Time, more in your face combat, but all we had so far is... 2 derp dives, starball in Z combo that's literally >>X but worse and shitty ZZZX, like what tf even is this? I would really appreciate some cast speed buffs too and better animations/effects (am I the only one who really enjoys effects on mod Guillotine? That's how effects on Metamorphy should work imo). Range buff for all skills from BtM onward when in Makeup would be kinda fun too ya know?
Aether Sage path... Well let's start from lore, where as High Magician she should already master all elements, so I think it's time to represent that in game and for El Lady sake, no, no more fire skills, cause she's really becoming Fire Mage with a bit of different types of magic. Her command fireballs range should be longer too, because Rose with musket has better range than her. Oh and don't forget to make her Memorize Passives from transcendence have at least a bit of synergy with Aether Sage passives.
Oz... Make her exist at least, please? Most of people wants dark mage that's really something more than all that stones, plasma and Angkor summoning, make her debuffs really kick your ass, her commands more fun to use (do you know that there's still XXvXZ combo? Yes, it's still shit) and use that shota kiddo in her Mod skills or at least make him appear in some skills. Make Oz great again... Or better at least.