Part of what you need to figure out is if you want sit-down Table Service restaurants, if you only have one day in each park. With the age of your kids, some of the places we liked:
MK:
Crystal Palace -- buffet, so you don't have to wait for food to be cooked. Fun interactions with Pooh characters.
If you discover the attractions are more inportant than the meals, then Pecos Bills, Columbia Harbor House or Cosmic Rays all have mobile order and are theme park food passable. Pinnochio Haus has upstairs seating looking out at Small World.
Epcot: when my kids were that age, they loved Coral Reef with the fish -- make an ADR on the first lunch seating to get down closer by the tank, or San Angel inside the pyramid in Mexico, watching the boat ride go by.
If not sit-down, then Sunshine Seasons in the Land has lots of options, and there is good quick-serve many places in world showcase.
Animal Kingdom: We love Tusker house, african-influenced buffet and characters.
Tiffins for a very special sit-down meal.
Satuuli Canteen for Quick serve (many other options)
DHS: When you are there, roundup rodeo BBQ might be open. Best food is at Hollywood Brown Derby. Okay quick serve at Backlot Express or ABC Commissary, but we like Rontu Roasters or Docking Bay 7 or Woody's Lunch Box.
Whereever you go, you will make magical memories. But if you do sit-down each day, you will eat up a lot of your park time, unless you want that kind of break.