Wow, these are some solid choices for breakfasts.
Crystal Palace is my FAVORITE, especially for breakfast. Keep that one for sure.
Cinderella's Royal Table is great, just for the experience of dining in the Castle. I don't really remember the food, but I'm sure it was good. I would keep this one because it is difficult to get a reservation in the first place.
I have never been to 1900 Park Fare, but my friends swears by it and says it is wonderful. So, keep that one too. The character interaction is different than other restaurants because it has a different selection of visitors, so you'll meet some new faces.
I have never been to the Tusker House for breakfast, but for lunch it is always DELICIOUS. So I'm sure breakfasts are very good.
I haven't been to Chef Mickey's in a while, (a good 7 years) but I remember the breakfast being good for us kids. However, I do remember my mom not being completely thrilled by it. So I am not sure.
Akershus has all of the princesses is one place, and I remember not loving the menu for lunch, but I think the breakfast one is much better. However, keep in mind that you are going to Cinderella's Castle already, and this is in a Castle too. however, there are more characters at this one.
So in all honesty, I'm not really sure which one to cancel. But I would say either Chef Mickey's or Akershus. I love them all though

but hey, there's always next time!