First off Eve is not real. She is as real as a 2D waifu. Thus, she cannot be best girl.
Ririsu is WORST girl, because SHE CAN FUCKING SEE THE PROBLEM, all she had to do was reveal that she was a girl then Eve would have disappeared. Instead, she basically allowed a fantasy girl to form and because he wasn't gay he ended up getting attached to a fake girl. I give her props for revenge though, not that he deserved it, but truly she has fucked up everything and has made everything worse.
Ebino is the best girl, not because she has big tits, but because she simply deserved happiness because she was the only pure maiden here.
The MC, we can't really blame him, because he literally had his "ideal girl" floating with him at all times. The big issue there though, is that he couldn't touch her. HOWEVER, the dude should have realized that Ebino was the only real option, as Ririsu was basically just being a bitch and Eve is ultimately only as real as his imagination is.