My girls, 2 and 4, liked US better - they have the Barney Show, Jaws, Kongfrontation, Woody Woodpecker's play zone, E.T. and the Nick studios. They are daredevils, though, and some of the rides they enjoy are geared toward older riders, but they definitely liked US better. When we visit MGM, it's usually only for 1/2 day and then we finish up our day at EPCOT.