Maybe odd choices for kids, but my kids love Raglan Road especially when there is live music and the Rose and Crown Pub where they can overlook the water and Illuminations if you time it just right. They also like T-Rex, Chef Mickey's for breakfast, and the Crystal Palace for breakfast or lunch.
My kids love HDDR (more for the show than the food) and Sci-Fi (more for the shakes and atmosphere than food) So to my kids it is all about the entertainment and not the food!
I just asked my son (he has gone 4x) to pick one favorite. He said he can't pick one but he can tell you his favorite. Tusker House Breakfast, CP lunch, CM, CRT and Hollywood ad Vine breakfast. I know out of all he eats the full plate in Tusker House, CP and Hollywood and Vine. CM and CRT he likes b/c of the character and the place itself.
I asked my 6-year-old (he's been around 23 or so times) but he couldn't pick just one. Some favorites: 'ohana, chef's de france (ratatoulle fan), chef mickey's, artist point, trail's end, sanaa, ca. grill (sushi fan), tokyo dining.