i actually think the biggest is disney world...but out of those...i can only say six flags cuz thats the only one ive been to. and from my experiences...six flags is beastt.!! haha i went to the one in new england, and i rode the bizzaro. it was amazing. they have other good rides too like the cyclone, the flashback, mind eraser, batman, and more. but i'd say the six flags in new jersey is better because it had the king da kah which is like the fastest biggest roller coaster everrr. plus they just built a bizzaro there as well.