The one that she wants to wear.
Seriously, I would hate it if anyone assumed I could be dressed up like a doll for their own amusement.
She has her own mind. Get her a gift certificate and offer to go shopping with her - and then go and don't complain if it takes up too much of your time, and be kind if she asks what you think.
Don't leave clothes on a porch for someone. It's creepy.