Hmm, I've had to change my opinion on some things/characters.
Firstly: Sion is my new favorite character. She has range if needed, the running is great when people use certain moves without checking distances, best launcher probably and when you add her supers into combos you can deal some serious damage. Also, her regular melee combat is very strong methinks.
Hisui is very easy to control and her supers are deceptively strong. Jump attacks are impossible, and she has very easy, very strong combos (or at least one I use all the time ^^). Finally, she has more armor than anyone else.
Nero: A nice mix of easily broken and unbreakable attacks that will make the opponent question his/her sanity
Nanaya: Veeeeery powerful in general. Deals much damage, but can't soak up much on the other hand. His cure is of course his guessing game. Mixing up the cutting moves, the invisible dash and jump moves and the "sabaku"-move can give you the win without even taking damage, since the opponent is either blocking or jumping in fear.
Akiha: Well... basically because she's untouchable in the air and you can get easy kills with suprise heat activation and using the Arc in close combat
) Easy kill right there.