Magic Kingdom.
The level of detail at Disney Parks is incredible.
Also, it would be nice if Kings Island had more ticketed events. For the most part it seems they do one event a year. Coasterstock being last season and this year being the ACE spring conference. Once you have a decent amount, if not, all the season pass add-ons, there is really nothing else you can do to elevate your day at the park other than maybe purchase some snacks and souvenirs. KI doesn't offer behind the scenes tours, no After Hours, no dining with Peanuts Characters.
I'll beat the dead horse of KI should also increase their season pass price to enhance the guest experience in the park overall.