I'd choose
Margot, it seems more lively than the others.
Greta and
Mared are my favourite
Margaret nns, but I prefer them as full names.
I've known two Marguerites, both elderly and both really interesting, intelligent women, so it's a name I have a good impression of, but I think it's a bit too fancy for me. One of them always went by
Daisy - not sure you could get away with that nowadays - and the other was sometimes Margi, with a hard g.