I love
Maia (MY-ah). I go back and forth between
Maia and
Maya. Today I prefer
Maya.
Gaia is fine, though I've never been a fan. I say GUY-ah but I'm sure there will be some people who say GAY-ah (even if just to tease her).
I adore
Kaia (KIE-ah) but only as a nickname (for
Katherine,
Katharina,
Katarina, etc). It's awfully cutesy as a stand-alone name.