Boma at AKL or Kona Cafe and the Poly are two of the best breakfasts from what I've read. Neither of these are character meals.
However, you don't say if you have kids with you and what you already have booked. If you have a young daughter that would enjoy princesses, I would suggest Akershus in the Norway pavilion of Epcot. I know the food is pretty standard but for the characters, I always hear of kids enjoying Chef Mickey's in the Contemporary. Also, as someone said, Tusker House in Animal Kingdom seems very popular. Crystal Palace in Magic Kingdom is also very popular for breakfast. All of these are character meals.