Disney is a theme park. Which means more for THEMING and SHOWS. Sixflags is an amusement, with badass roller coasters. There is no way to compare them, so why are you trying? Six flags vs. Cedar Fair would be a good comparison. Also, next time, use a poll.
Again apples and oranges. They're designed for two different things. Disney is more of a family place and, as disaster said, its a theme park with shows and theming. Sixflags is more for thrills and adventure. Its all a personal preference.
Funny thing is, more people die at Disney than most coaster parks, I think. You hear about deaths at Disney all the time in the news (Well, maybe not everybody, but I live in the Orlando area). That can probably be attributed to the overwhelming amount of old, sick, and fat people that go there for their children, grand-children, etc.