At MK, we love to go to Columbia Harbour House, it is one of the semi-out-of-the-way places. It is never busy and they have a great salad that I enjoy as well as a variety of sandwiches and of course the classic chicken fingers that you can just about anywhere at WDW. I'm also a fan of Cosmic Ray's, they have pretty good burgers as well as a good variety of other foods.
At Epcot, Nine Dragons has great Chinese and we also love the cs place in Mexico (can't remember the name right now).
At MGM, great variety at Backlot Express.
At AK, we always go to Tusker house. I don't believe they have burgers, but the food is great!
As you can see, I have more input on the MK restaurants as it seems we always find that we're hungry while there.
As far as DTD, we always eat at the express Wolfgang Puck restaurant. Don't recall the exact name, but the food is great and it is different than your typical WDW foods.
Happy dining!