Another contradictory opinion - my kids and I love EPCOT! I have a 15 yo DS and a 12 yo DD and it is their favorite park. EPCOT has more than you first think- Soarin', Mission Space, Nemo, Test Track, Spaceship Earth are some of the bigger rides. Plus each country has a ride or movie associated with it. My kids also like all the varieties of foods available. The Disney folks have added a lot of interactive exhibits and extras around EPCOT, which makes it fun. I would say it depends on the type of people you and your kids are, though. We tend to be the nerdy type that enjoys learning about how things work and playing with tech stuff. Of course, Magic Kingdom has the most rides overall.
I personally don't like Animal Kingdom very much. They only have about 4 rides worth going on, IMO, and each ride is in a separate area of the park. You have to walk pretty far to get from ride. And it drives me crazy because there are so many design flaws. I feel like the walkways are the smallest and most crowded of any Disney park, and many of the bathrooms are small and only have one door. It drives me nuts because the park was the last one built. They know how many people visit Disney each year, yet they seemed to design it that way on purpose.
Hollywood Studios is great for Star Wars buffs. The ride is newly designed with many different scenarios. We rode it 3 times in a a row and it was different each ride. They also have a great car stunt show and an interactive Toy Story ride in addition to Tower of Terror and Rockin' Rollercoaster. They have a few other stage shows and lots of character meet and greet opportunities.
What kind of personalities do your kids have? That will help us to give you advice.