Out of the girls that are just from boss drops, Kimie is easily my favorite. Her 2 and 3* avatars are really cute Of story girls, I like the ninja spy's alpha (she's both pretty and badass) but she's annoying me by not joining my harem, so instead I'll go with Red Battler :P Jennie's sister is probably my favorite NPC.

Honorable mentions go to the Great Fairy, Princess Agate, and the two other girls in the king's harem. So, pretty much every girl that appeared in the Gems Kingdom.