That's all a matter of opinion, really. I use SakuyaA, because it homes when focused and is spread when unfocused, which is really what you need. SakuyaB doesn't hold a candle to SakuyaA. Both of Marisa's aren't really good, and her "special abilities" aren't too great either. ReimuA and ReimuB are both good shot-types, plus she has the smallest hitbox, but I tend to use SakuyaA a lot more because she gets the job done.
It also depends on what in the game you are trying to do. Reimu's hitbox makes more of a difference with denser patterns, so some might prefer her for hard and lunatic mode, for example.