The Buff that Annie Really needs...
is her wave clear.
Annie's kit is just outdated and imo, is in need of a rework. But she is not on Riot's radar for getting a rework and she will get buffs on 8.17. The auto attack damage revert would just make her annoying in the bottom lane like when she would just auto and Q the enemy team with safe range from her 625 auto range. She needs to be buff to what she's clearly outdated at, wave clear. She gets easily out pushed by almost all mid laners due to her mediocre wave clear that she maxes second most of the time.
Here are probable buffs that would help Annie imo:
More Base Mana
As an Annie main, one of the reasons why I like playing Annie is because she has a very flexible build path. With her Q refund, she wasn't mandated to buy mana items, but as of now when they nerfed mages' mana items, she became more mana reliant and building mana items are more needed than before.
Lower Her Mana Costs
Her Q costs 80 mana at maxed ranked and her W costs 110 at maxed. If an Annie player maxed W first to match the enemy mid laner's push/roam, she will sacrifice her dps with her Q having a lower damage. This is not an issue to updated midlaners because most of their basic abilities are aoe and with just one mana item, they'll just easily combo the wave with their basic abilities and would have more mid control than Annie.
Buff her Incinerate (W)
While this has the ability to stun multiple enemies, it's short range and is mostly maxed second and her only "faster" wave clear ability. The width could be buffed for a slightly wider radius for it could reach more minion waves. Or it could just deal % more damage to minions/monsters if Annie has her passive.
Not all of these are needed to give to her just even one of the options would be good enough. All in all, Annie just needs an update on her wave clear and that's the buff that we Annie mains would love to have for her.