I usually eat at the resort in which I'm staying for breakfast either with the Concierge perks or in the resort restaurants. But I usually make a point to go to the Crystal Palace once for a character breakfast. It has the Pooh characters which are favorites of mine and it is well w/in the park and so an early breakfast there and you can get rolling on your day.
I hear LTT is a nice experience, although I myself haven't been there for years. I'm thinking of trying it out for dinner in a couple weeks.
The Breakfastaurus w/ Donald is supposedly wonderful at the AK, but I haven't tried it myself.
Eating BF at the World Showcase is fun, esp. if you are in a hurry. You can pick up some pastries and coffee in France and be on your way.
And if you are staying at a WDW resort, the resorts have some really nice places to eat BF. I hear CM is a must see, 1900PF is fun, Boma's is delish, Spoodles was marvelous, CM Cafe is a delight... and many others.
Hope this helps a bit.