Last trip we did both breakfasts. DD is a huge Cinderella nut and we wanted her to meet Cindy in the castle, etc. It helped that it was my birthday, and that was a neat place to celebrate first thing in the morning! The food was just OK. Nothing to write home about.
A few days later we did Storybook. No Cinderella (unless you count DD, who again wore her dress

) but the character interaction was great and the food was very good.
In November, we are doing Storybook and then Cinderella's Gala feast. That dinner will be new for us. This way, we get in one princess breakfast, and still get a meal with Cinderella. We will probably have dinner in the Castle once, anyway.
My adviceif you have never done them, do them both. This way you can experience them and decide what is better for your family.
DD saw Belle at both breakfasts. Belle #2 at Storybook glanced thru DD's autograph book and noticed it was signed by Belle already. She asked DD if they had met already, since DD looked very familair to her. I thought that was a nice touch! DD was only 3 at the time and may not have noticed any differences.