We (to adults) just returned....we did all the parks and at the end agreed the MK is our favorite for the reason that you've got so many options there. Specifically Main Street, U.S.A., Adventureland, Frontierland, Fantasy land, Liberty Square and Tomorrowland each of which has its own unique feel/mood/ambiance (whatever you call it
).
More than that if this is your first trip MK will make you want to visit again and again, something which I'm not sure if the other parks can do (folks? am I way off?) *Mind you I adore all the others, but if down to picking one...
You mentioned thrill rides...I found Mission Space to be a dud. While they did a great job of letting riders experience g-force in the end it's more virtual reality than a "ride". As for the Rockin' Rollercoaster at MGM is indeed great! So great, in fact, that I went on it repeatedly. Still, I wouldn't trade even the best rollercoaster in the dark (which it is!) for the complete sensory experience you get from Thunder Mt and/or Splash Mt.. Besides MK has Space Mt which is still pretty darn good!!! Also, while not a thrill ride, there's the Buzz Lightyear right which is just great fun. Oh ,oh
AND then you've still got the classics; Haunted Mansion, Jungle Cruise, Pirates of the Caribbean!!!
Yup
hands down, it's gotta be Magic Kingdom!
Cathryn~