Your kids are my kids ages, and my kids love to ride. I would say Hollywood Studios for these reasons: Tower of Terror, Rockin Rollercoaster, HSMusical peprally show, Beauty and the Beast show, Muppets 3D Adventure, Tower of Terror, Tower of Terror, Tower of Terror. Guess which ride is our favorite??
I would pick AK second, for Expedition Everest, Dinosaur, Kali River Rapids, Kila...Safari, the Bug's Life Show, Lion King Show (awesome!), and the DinoLand part with the dinosaur ride that is practically Dumbo with half the wait time, and there are other cute rides in that area.
There are a few rides at Epcot, but not hugely fun for us. We did love Soarin' and Test Track was okay, not as exciting as we'd heard hype about. We did like the Living with the Land informative boat ride, but I think Epcot is more about the food than the rides!
Did you want a simple answer? I can get chatty, apparently!