My niece and I did both of these meals in March and although we thought both meals were good we both preferred the Dinner (favorite meal of the trip).
We found the breakfast to be your standard character meal. Character interaction was ok, pretty brief, the Mad Hatter is entertaining. Food was the usual breakfast stuff.
To us dinner seemed to be very unique. Food was good, standard buffet. Character interaction was amazing. All of the characters joked and played around, lots of interaction. We had an 8:00 seating so it was getting to be the end of the night which may have been why we had such great interactions with all characters (step-mom and sisters came past our table a couple of times, step-mom hung around and was tying the vail from my mickey ears into bows).
I think it all really comes down to what characters you would prefer to see, and what type of meal you are looking for. The breakfast is more calm and relaxing (although the Mad Hatter can get a little loud). The dinner can be a little more unpredictable and loud with the step-sisters running around but we found it way more entertaining.