MGM was our least favorite. Other than Muppetvision 3D and The Great Movie Ride (which I loved), there reallly was not much else we enjoyed that much. The stunt show was even so-so to us.
When my kids are a little older and more adventurous, they will probably love Rocknrollercoaster and Tower of Terror. We still go to MGM, we just don't stick around too long.
Our fav is also MK, with Epcot a close second due to Test Track and Soarin.