Aether is very powerful, but will take some investment in order for you to be able to maximize her potential. First off, her passive allows her to generate 15BG instead of 10BG per normal hit. So that means, as long as she DATAs, she will easily catch up in burst despite the constant -10BG drain from abi3. To do that, you have several options to consider:
- Shingen buff, very weak but better than nothing
- Titania
- Acc with DA and preferably TA buff
- After WiCat is released, Tiara set
- Azazel AW, when she gets it
- Also an option, Summon actives such as Fluffy / Aratron
Personally, I've never had any trouble getting Aether to catch up. In fact, she's faster than most Wind SSRs on my team once I got her DATA consistency going, even though everyone's already equipped with Tiara sets. She's currently placed on the 3rd slot of my team, with only Cu in front of her.
P.S. Obviously, accidents can still happen and you should improvise whether you want to use abi3 when you are preparing an FB next turn, or when you don't necessary have to use it because you already have a good number of stacks, or when you are racing for MVP against other players and can't afford to lose time for long buffing animation.