My favorite Sunshine girl is You. 2nd would be Riko. 3rd would be Ruby. After that, I think that Mari and Chika have some potential, but I have to be honest, Chika kinda pissed me off in the last two episodes, lol.
I really like You's character overall. She strikes me as hitting a good blend between military otaku tomboy and fun-loving friend-valuing genki girl. Riko has a very nice elegance and sweetness to her. I like the Dia/Ruby dynamic, and I find Ruby a little easier to take on an individual level of the two Kurosawa sisters.
I loved Hanamaru in Episode 4, but I felt she became a little too comedy character-like after that. Maybe she'll bounce back some in Season 2, and I think Hanamaru has good potential.
I have mixed feelings on Yohane, but she could be funny sometimes at least. Kanan's minimal screen-time makes her hard to evaluate, and I felt the 3rd years drama kinda flopped.
But yeah, at the top-end, at least I liked You and Riko and Ruby a good amount.