I'm kind of curious how this is going to end. Like, the transfer girl "winning" would be kind of a let down, because that's just maintaining the status quo, right? And then having the rivals as such major characters would be pointless. But any of the other three girls winning might feel a bit odd because at the moment they're all pretty equal. So I feel like it'll be one of them, but as for which one... I guess it depends on how they develop throughout the story?
Which is cool, I think, because the fact that this premise can't really work without proper character development means that it'll probably actually have that, which would mean a proper arc towards one of the other girls rather than just a phone-in at the end like other harem manga tend to have. (Assuming they don't just go with the "first girl wins" and call it a day.)