I think I liked black a bit more since it just had more of a deredere feel attached to it in the anime for me. But I ended up voting for both since red haired Shana just screams cool especially with that leather suit from the 1st few eps of season 1.
I honestly like both~ She looks very cute and she does have her moments!
Black hair is like cuteness and Red is kick ass!!
It's like when girls go from normal to PMS mode hahaha....ahem you know?...right?