Also, with respect...to add to OhThePain's response, the choice of restaurant will depend on the type of dining experience you are seeking. Many of the restaurants are fine dining with excellent food in a formal atmosphere (signature), some are more casual with average food but better pricing, and some are uniquely Disney World. Some are character dining, some are buffets. Most require ADRs (advanced dining reservations). Be prepared at 180 days before your trip to make your ADRs. Also, be prepared to wait a little while for your table and estimate 2x the price you would pay elsewhere for the same food. With that said, here are some of the most popular restaurants (that are also on our list of favorites)
MK: Be Our Guest (strictly for the unique atmosphere. the food is barely average).
HS: 50's Prime Time (for the unique experience and the fried chicken)
HS: Sci Fi Diner (for the unique dining experience)
EP: San Angel Inn (beautiful atmosphere, good food, affordable).
AK: Yak n Yeti or Nomad Lounge (good food)
DS: Morimotos (beautiful, try the ribs)
Resorts:
AKL: Jiko, Sanaa, Boma...all great food
WL: Artiste Point
Poly: 'Ohana
Honorable Mentions: Yachtmans, Le Cellier, Via Napoli, Tiffins, Brown Derby, Skipper Canteen.
To name about 20 of the 300 choices....
Good Luck!!