Ava if you like simplicity. It’s pretty, easy to say and spell, fairly diminutive proof and a cool palindrome name to boot. I just wish it wasn’t so trendy - you don’t meet elderly or even middle aged Ava’s (Ava Gardner is long gone and her name wasn’t a big influence at the time afaik). you’d have to hope that it stays fairly popular now and doesn’t feel dated in 40 years.
Isabella if you want something a bit more classic (you DO meet middle aged and elderly Isabella’s, although they are rarer in this country and Isabel/Isobel more common). It also has lots of diminutive options, so is a “safe” choice in that if she dislikes it, shes got Izzy/Elle/Ella/Belle/Bella etc to fall back on. The downside is that as a 4 syllable name it is very likely it will get shortened by most people, especially as she gets older- how would you feel about that? If you dislike one of the nn options , I’d introduce her by another one from Day 1.
While I personally love Maya pronounced the “May-ah” way, it’s the trickiest of your options - two accepted pronunciations in the UK, and a variety of spellings seem around too (Maya/Maia/Maja/Myah/Mya).
All the names are lovely but if you like the names equally, on balance, I’d pick Ava.