I always find it hard to personally choose who I think I'm best with. In the end, your best will tend to be the characters you put the most effort into. Who I plan to put the most effort into;
1) Rachel
2) Helena
3) Lei-Fang
4) Hitomi
5) Kokoro
To be honest, probably not in that order hahaha. I tend to switch characters at least twice a week, which tends to be my downfall cause I end up okay with several characters, but not great with any! -_-