1 or 8
Blue is the right color, none of the pinks seem right to me. But dress design with twintails just seems more cohesive than the apron, and the flopped rabbit ears don't quite look right with the apron-girl's hairstyle, so I would really prefer 8 with twintails and the double ribbon, or 1 with 8's complexion and hair color. Or 6 with blue clothes and green eyes.
IDK, I don't think there's going to be any consensus on colors though.