I voted for:
Otabe: Because she's still awesome. She seems almost like she's waiting for something, and I'm getting the vibe that she repeated those years on purpose, but I could be totally wrong.
Yoga: Because Annin is an awesome yankee, as she proved in MG3. She's a bit less badass in this, but still. Her devotion to Salt only makes me like (and feel bad for) her more. From what I've seen she's quite possibly the only queen so devoted to the president, it reminds me of Yuko's Rappapa.
Kobii: I really do like Milky in this role. I like her, for lack of a better word, bloodlust. The fact that she had the balls to go against her leaders orders is intriguing, and I'm curious about what she can do in a one-on-one fight. Maybe we'll see soon.
Kojima: Torigoya returns, and I was beyond happy to see her! The former queen showed the current students how it's done!
I also like Okada Nana's character, based on what little I've seen of her. I thought she did quite well in the scene where she nearly hit Sakura.