We haven't done the castle. My daughter is no more entraced by Cinderella than any other princess. PSB is also in a castle (Norway) though not THE castle.
We saw Jasmine, Mulan, Belle, Aurora and Snow White at PSB for breakfast. Its my understanding that Ariel shows up here for dinner.
PSB has the advantage of being somewhat easier to book (at least that is my impression) and less expensive.
My own two cents is to see what works in YOUR schedule and not worry too much about what might be slightly better or worse (unless your DD has a need to see a particular princess or a need to go into THE castle). We were staying at BW, so PSB was much more convinent for us.