I've never read
Hamlet (yet) so the Shakespearean connection doesn't bother me. I doubt most people would even know about the connection. I think
Ophelia looks very pretty, but I'm not as fond of the sound. To me it sounds like "oh-feel-ya." For that reason, I prefer the Spanish
Ofelia, which is pronounced slightly differently.
I've never been a fan of
Gillian. I also don't like this spelling, because it makes me want to pronounce it starting with gill, like the gill of a fish.
Jillian looks nicer in my opinion. The nickname
Jill is avoidable, I think.