If someone were going to WDW for the first time and could only ride five rides, which should the definitely do. I think that's somewhat different than your "favorite rides." For example, I think Muppet Vision 3D is a "must do," but I don't go ride it every time I'm there. So my "Must Do 5:"
Splash Mountain
Expedition Everest
Muppet Vision 3-D
Tower of Terror
Space Mountain
Wow...I have nothing from Epcot?