Hi Katie!
Oh, both parks are such good choices. I'll lay out some fun things for you to do at each park and then you can choose, ok?
Animal Kingdom has some great trails for you and your kids to walk through--full of animals and even some hands-on stations. The Festival of the Lion King and the Jammin' Jungle Parade are some of my favorite attractions ever. Plus, at Camp Minnie Mickey you'll be able to see all your favorite characters for autographs and hugs. If your kids love animals, this is definitely the place to be. Animal Kingdom also has a decided slower pace to it.
Hollywood Studios is the place for characters---do your kids like Playhouse Disney, Kermit and Toy Story? They'd see all of it here! The Playhouse Disney show is the best of the best--interactive and full of all the familiar TV characters. The shows (Beauty and the Beast and Little Mermaid) are fun re-tellings of the movies.
Both parks also have a playground--Animal Kingdom's Boneyard and Hollywood Studio's Honey I Shrunk the Kids Set.
I really can't decide. They are both so fun! And both my favorite! Is that possible? You might want to check out the
Magical Beginnings Guide. It's a fun kid-friendly map that highlights the best attractions for the younger set. Maybe you can make a list of pros and cons and see which park wins!
Either way you're going to have an amazing vacation!