Chiaki by far
Miu second place.
Mikan is cute. I feel bad for her and I hate how her fans are horneyposters
Baconhands is cute, but she doesn't stand out.

I hated Celeste my first playthrough. I thought she was just a bitch. She grew on me on the second playthrough. Her design is cute and I do like her snarky sense of humor.

Honorable mention: Mukuro