Maia,
Kaia and
Gaia in that order are first because I like the look of the i.
Maia is sweet,
Kaia is different in an okay sort of way and
Gaia is nice, but a bit too out there.
Then come
Maya, Kaya,
Maja and
Kaja, but I'm not too keen on the j's.
Then
Mya, Kya, Caia and Caya becuase not having the first a makes
Mya and Kya look incomplete and the c's in Caia and Caya just look forced and silly.