My 5yo enjoyed all the rides that he was tall enough for, but he's a daredevil. He only wanted to do Dinosaur once, which meant that he was scared (he'd never admit to being scared to I have to base it on his willingness to go back on the ride). He did Tower of Terror several times, but eventually chose to stay with my mom instead of ride again. Start out with the more gentle rides and work up from there.
T&B