We did pretty much all the in-park character breakfasts possible in March, and I really don't have anything bad to say about any of them.
MK: CRT, of course, but Crystal Palace is also good, and probably the best food choices of any of the buffets. Of course, it helps if your kids (or you!) are into Pooh and the gang.
AK: Tusker House is a very good breakfast, with 4 of the "fab 5" (Minnie isn't there), and the only place you can find Daisy at a character meal. If you get an 8 AM reservation, you should be able to walk onto the Safari after your meal.
Epcot: Akerhaus is a good option if you like princesses, but (at least when we went) the park will be open well before you're finished, even with the earliest ADR.
DHS: PHD at Hollywood & Vine probably ranks at the bottom, simply because the characters have more limited appeal. For us, our oldest is a big Little Einsteins fan, so this was a "must do".
Don't completely discount out-of-park options. Chef Mickey's, 'Ohana, and 1900 Park Fare are all on the MK resort loop, and easy to go to and from MK. Cape May is a possibility if you're going to go to Epcot or DHS. (Of those, the only one we did was CM.)