What constitutes as too popular for you? (Top 100? Top 500? Top 1000? Used more than 5 times in the US last year?)
It's a little hard to help with more suggestions when your responses are "I love them all and they are too popular"
esp when you get suggestions like Liriope, Sophronia or Fiorella - all of which seem to fit your girly, sweet and uncommon requirement.