Millie is at least as good as the names it's typically short for. I'd rather be a
Millie than a
Mildred or a
Millicent.
Maisie and
Violet are equally awful, and
Davina is fine as a mn but only if it's honouring a
David.
I like
Jillian mildly and
Gillian a lot - enough to use. Jilliana looks like a mistake for
Juliana and if I met one I'd have to fight to control my features. (For the record, I don't mind
Juliana - though it's very
Dutch royalty - but it's too long to stay
Juliana and I don't find
Julie even a little bit interesting.)