Top 3 might be
Vili: I don't know, I just love her.
Amy: I wasn't expecting a chimera type girl and she cute so yeah (I liked some of xelvy's girls in mgq).
Tabitha: I like shy/awkard I guess, plus she's a bat girl (there aren't many of them in monster girl stuff).
Also, after talking with Venefica, I want a contract with Vili so I get new dark magic spells. I mean, she doesn't have nothing better to do.
There's more I could mention, but that would defeat the purpose of choosing favorites.
A type of monster I'd like to see... I would say lamia, but since we have Jora who's similar, I'll say a fairy or dullahan.