At Magic Kingdom, the rides are as much of the experience as the parades, shows, and food but are they worthy of multiple or repeated experiences?
Some will tell you that hitting Tron: Lightcycle Run is a must ride. It's o.k. but if I go to the park the draw to ride it is typically more exciting than the ride itself. Yes, the first 5 seconds is amazing but after that, it kind of becomes another Space Mountain.
Space Mountain is fun as well and while it too is worthy of multiple experiences does it pull in that "must-ride" every time you are at the park? I'm not sure if we are being honest.
Looking over the M.K. map of attractions, there really isn't a singular ride attraction that has an absolute must-do each and every visit. What makes M.K. fun is that you actually don't have to do anything to have a great time.