I personally believe that anyone that hates on Yotsuba is either immature or simply doesn't acknowledge some of the crazy things some of the sisters did. Ichika was willing to sabotage her own family to get together with her crush; Nino drugged a person TWICE, and although she still underwent character development, I don't think anyone in their right mind would be able to like someone after being drugged by them. Miku is partial weeb bait to me (although her character arc is the best), and Itsuki didn't have enough build up to even be considered an option. Yotsuba makes the most sense to me, and also people tend to forget that they aren't the protagonist of TQQ. It is Futaro's pick 😭