Oh my lord, I love this game. I would have beaten it again already except Halo is eating me. If you don't own it already, you should buy/borrow it from someone! I admit, it's a little out there and short, but very fun.
Anyway, I love every single design from Polka to Princess Serenade, but Falsetto and Viola are my favorites (I like Claves because her look reminds me a little of Utena, but I kinda hate her character). Ahh, so many great designs!