I'm not sure. I've had Skye in my town before and just recently moved her out. She was a real sweetheart and all, but she never really pinged me all that often or asked for favors. That might not have any bearing on your decision since it might be different in your town but at one time I found I didn't like her as much as I thought I would due to that.
On the other hand I absolutely love Fauna, shes adorable lol. I havent had her in my town yet, but I have a weak spot for the deers, especially the female ones.
I can't really speak for Lily since I'm not too fond of the frog villagers.