Walt Disney World has some delicious dining options, but some of the very best ones are found at Disney's onsite hotels.
The hotel restaurants are usually quieter and it can be much easier to get a dining reservation. The quality of food at the restaurants is usually better too, even the quick service restaurants.
Disney Springs, the entertainment district, has lots of options when it comes to dining. Similar to the hotels, reservations are generally easier to find and you can even walk up and get a table straight away at some places.
If you aren't on a Disney Dining Plan you should also take a look at the restaurants over at the Swan and Dolphin hotels, which are a short boat ride from Epcot and Hollywood Studios. The restaurants are some of the best on property and they even offer a character breakfast.
Dining in the parks is fun but generally you get a better dining experience elsewhere.