My kiddos are 3 and 5 and have been to Disney three times so far. Here are their big picks:
Magic Kingdom: Be Our Guest (breakfast)- its so fun to explore the rooms and they got a little pastry platter that they enjoyed, Crystal Palace was nice but felt a bit crowded and noisy when we were there- great if she is into seeing characters, Cinderella's Castle was amazing for my little princess dressed up as Cinderella, but no one in our party really liked the food. We ended up getting snacks later after dinner
Hollywood Studios: definitely Hollywood & Vine- the Disney Jr. characters were amazing with interacting with the kids and the tables allowed enough space in between to get good pics (Doc even gave my daughter's Lambie a checkup)
Animal Kingdom: Tusker House- the characters come around which is exciting and my kids loved joining in the little parade, buffets also are easier with little ones to eliminate wait time
Epcot: Still haven't found a favorite for them... the ice cream is usually to blame for them not eating oops!