I like
Ophelia because it is a beautiful name. I think it is pretty tied to the Shakespeare thing... I can't say for sure how many people would not know about it.
Gillian is way cute. I admit I like it with a hard g, but it seems most people use the soft g. There is definitely something earthy and elfin about it. I'm not sure if
Jill is unavoidable.... I wouldn't use it, but some people might.