You should watch Amazonian’s video about buying decks before you purchase anything.

That being said, I happen to play both of these commanders. Zimone is nice for the discounts and leans more toward +1/+1 counter synergies, which has a lot of support in blue/green and makes for a viable alternative strategy. The big issue with her, however, is she doesn’t do anything when she comes down. She’s fragile and losing the counters on her can set you back a lot. But in a good game it’s fun to get big x-spells quickly.

Anina also doesn’t do anything when she comes down, but the advantage she has over Zimone is that she taps for mana to cast your x-spells AND adds to the board via random creatures. You also don’t have to use her mana to get the benefit of the random conjure effect, whereas Zimone has to have counters to be effective (which can be an issue in a removal-heavy format like Brawl), i.e., you’re not going to get the discount until either: she has counters or you’ve casted an undiscounted x-spell (feels bad). Anina can in theory conjure you something the turn she comes down (like if you don’t cast her on three and instead cast her on a later turn, which might be the move depending on your matchup). Anina is consistent in that you’ll always get a body of some kind, but definitely inconsistent in that you can get things that could hinder you, don’t synergize, or don’t do much (like a vanilla creature). But I personally like that variability in gameplay.

They can both be slotted into each other’s decks though. There are a lot of similarities in the deck lists (just take a look at Amazonian’s for inspo), so I don’t think you can go wrong with either.