I think there are different ways to look at it. Are you into thrill rides or nostalgia ... nostalgia plays a big part for us at WDW ... so while Spaceship Earth may not be thrilling, we can't pass through Epcot without a ride.
We do Universal less often ... went for the first time in three or four years in December. To me there isn't much nostalgia there, so it is all about the rides. We are more Harry Potter people, so the three HP rides - not huge multiple upside down roller coaster people - so after HP, I'd probably go with Transformers or Spiderman.
At Disney, RoTR and FOP are hard to beat for theming / some thrills / overall experience. Then on the higher thrill side I'd go with Everest, Rock N Roller Coaster & Tower of Terror. That being said I am not a thrill person so I'd probably choose Haunted Mansion, Spaceship Earth & It's a Small World, lol.