I'll give you not one, but three (and, IMO, you can't go wrong with
any of these choices):
Boma--It's a breakfast buffet, sure, but with a twist. If you want to get a bit adventurous, this is the place for you, with several African-inspired selections. And, if all you want is hearty traditional English (and, by extension, American) breakfast fare, all that is here as well, including an omelette station. (FYI--they also serve a traditional Japanese breakfast here as well--though I didn't try it.)
Crystal Palace--Another breakfast buffet, but certainly a top notch buffet, and one with characters, to boot. Also, if you can get your ADR for first thing in the morning, right after they've opened up,
and you don't wait around to interact with every single character there (Pooh characters, BTW), you just might be able to get a meal in and then line up at the entrance to Tomorrowland, say, thereby getting in line for your favorite attraction before the park even officially opens. (And when I say "getting in line", I mean lining up at the roped off entrance to the Magic Kingdom land of your choice.)
Kona Cafe--A charming, relaxed atmosphere at the Poly which is, of course, on the monorail line. And I'm convinced nothing beats starting your day off with some Tonga Toast, some sausage, and a divine cup of Kona press-pot coffee.
Anyway, HTH!!