Martha - really don’t like - because of dreary Martha in the bible
Clara - very nice! And not hideously overused
Alice - nice but many of them - depends if that bothers you
Anya - I find it a bit meh, prefer the classic Anna
Eva - like Alice - nice but there are many Eve/Eva/Evelyn/Avas
Thea - very meh, though Theodora is lovely
So I like Clara best! Other thoughts - Stella, Bea (nn for Beatrice), Emma, Pippa (nn for Philippa), Lois, Ines, Caitlin, Robin, May (very overused as a middle name, but not as a first name), Iris, Hannah, Frances, Lara, Lauren