Hi Crystal,
Thanks for visiting Disney Parks Moms Panel. I love your question, and I'm sure each of us here on the Panel would answer just a bit differently.
My first answer would be to consider a Park Hopper Option to enjoy same-day admission to all 4 theme parks and experience the best of each park. But let's say you want to visit only 3 parks.
First, no vacation to Walt Disney World is complete without a visit to the Most Magical Place on Earth, so Magic Kingdom is a must-do.
Disney's Animal Kingdom also makes my must-do list. Festival of the Lion King and Finding Nemo - The Musical are two of my favorite performance shows, and Expedition Everest is one of my favorite ride attractions. With the addition of Pandora – The World of Avatar and the simply indescribably awesome
Avatar Flight of Passage, I think Disney's Animal Kingdom is an easy choice.
Now comes the hard part — Disney's Hollywood Studios or Epcot?
If your visit were later in the summer, I'd say Disney's Hollywood Studios faster than Sheriff Woody says "Reach for the sky!" because Toy Story Land is opening. Still, if the Force is strong with anyone in your family, there is more than enough galactic great fun to enjoy. Disney Junior - Live on Stage! is also a fun dance party for your princess.
Epcot is where I love to walk the World Showcase, go Soarin' Around the World, eat amazing foods at the country pavilions, and stare in awe at IllumiNations: Reflections of Earth.
So, if I'm feeling more Jedi, I'd visit
Disney's Hollywood Studios. If I'm feeling more globetrotter, I'd tour Epcot.
Enjoy your Disney!
Jerry