I like Thalassa, Asteria, Sophrosyne, Melinoe,
Adrasteia and
Niobe.
I dislike the Leuco in Leucothea etc. because of the disease connotations, and many of these names feature consonant groups that I personally am not fond of... but the above listed are very pretty. I find Melinoe particularly interesting - a little internet research suggests some rather weird mythology around her, but it's nice all the same.