Anivia is now manaless

Manaless Anivia would be, hands down, the best champion in the game. She could just sit ult under your tower and she'd get perfect cs while you were stuck with farming under turret until creeps inevitably took tower. Also, current Ekko isn't even that good (in solo queue at least), he's just got an incredible mismatch between his best outcome and his typical outcome, where in his best outcome he can 1v5 easily and in his typical outcome he's just a flashy but less reliable Diana/Fizz; because of confirmation bias people remember Ekko ulting into 4 people and instantly winning a teamfight and not Ekko being forced to ult early and doing nothing in most other teamfights.

I think anivia can outdamage him once she hits 6, but anivia is an odd champ

her ult is supposed to be her go to and her wall is supposed to corner champs, but it's not unable to be passed like the description, as it can be dashed over and flashed over and blinked over

but with her wall, ekko would have a harder time sticking to her unless she stayed in one place

I highly disagree. Anivia is a great champion, as is Ekko, but comparing them is absolutely stupid. They fill completely different roles. Anivia's a zoning mage that can defend, push, and kite extremely well. Ekko is an assassin/occasionally bruiser that goes all in and has a lot of mobility. Anivia is clearly better in some aspects while weaker in others.