As a kid, I was more interested in going on the Mountains when at Magic Kingdom. Now that I'm older, I prefer the rides like Pirates of the Caribbean and the Haunted Mansion. Ironically both having been the base for movie adaptations, with Pirates clearly being the better of the two.
Pirates of the Caribbean is a slow moving boat ride through what I assume is now re-themed as Tortuga from the movie. Although I have been on it before Pirates came out in 2003, I don't really remember it too much before Jack Sparrow and Barbossa was introduced to the ride. The classic elements are still there, and various pointers to the films, but overall the ride has improved in recent years due to the films success.
By no means a thrill ride, but it's the theming and attention to detail that makes this one of my favourites in Magic Kingdom.