I have to admit, I used to be solely devoted to Charlotte, but after seeing Kanzashi and Tatenashi in season 2 and the Ignition Hearts game, I can't choose who my favorite girl is between the two of them.
Though Charlotte still remains high on my favorites list since she's at least more understanding than most of the other girls.
And for those wanting to see more assertive Kanzashi, I refer you to her ending in Ignition Hearts. Seeing her putting Ichika in a Hime-Sama Dakko was quite amusing.
Between Ichika's density, it makes you wonder which of the two of them would be the dominant one in a relationship.