Well...It's definitely impossible to choose. Considering that choosing one over the other makes one of them...sad, and also you wouldn't have good reason to have sex with them both anymore.
So obviously the answer is both of them, right? As a Hentai Protagonist, that is the only possible answer.
That ending though...Good luck convincing them, I suppose.
Ya'll took this shit to an entirely different level, i'll let microwave get back to eating his bowl of dicks for breakfast and read his "good intelligent jokes" in the comment section.