1. Good Sevice - Unpleasant employees and slow and/or incompetent service annoy me with any theme park or business.
2. Cleanliness - I'm a neat freak so I care about the cleanliness and, in my opinion, is almost as important as good service. A clean park to me indicates the company takes pride in their appearance and the image they present to the public. And after all, who wants to go play in a dump?
3. Attractions - While number is important (who wants to spend money to see only a few attractions?), crappy service and a dirty park will put enough of a damper on my experience that I won't be able to enjoy the attractions even if it's a fair number. For example, my last trip to Disney, I rode at the front of the monorail for the first time. I was excited, but the driver was silent the whole time and would only respond to my two questions with a shake of the head. I didn't talk any further 'cause it was clear he didn't want to chat.
This list is the same for Disney and non-Disney theme parks.
Joe