Leia: I like the look & the sound, but not so keen on the 'princess' association for a little girl, even if she was a cool princess.
Léa would be less obvious; I think
Leia looks better though.
Moriah: gives off an American-religious vibe to me, and would probably be written as
Mariah a lot. But it could grow on me, I like the sound
Mattea - sweet and refreshing, I've never met or heard of one here.