For a girl I think anyah or Anastasia is rare. And they're both pretty.
For a boys name, demetri or Demetrius are rare.
you could always try a different spelling to a more common name it make it unique
Me and my husband picked out a boy and girl name before we found out what we were having. Found out we are having a boy and his name is Asher. Our girl name was going to be Hadley.
Eli n zion are my choices when our if i get a boy. Of course i keep getting girls lol