This may be the wrong forum to be asking about Non-Disney Parks. It is a VERY Disney centric crowd that most have an actual aversion to leaving property and that negatively colors their opinions when they do.
SeaWorld is a nice park, but very show heavy. They have added several attractions in the past several years that are pretty amazing. This year they opened Turtle Trek, which is the most amazing 3D theater attraction. It has the screen in a dome above your head and creates the most immersive theater attraction environment I have experienced. 3 years ago they opened Manta, which is a great flying coaster that is VERY high on the thrill factor. And the queue is a rock cave that winds around a large aquarium with 300+ rays. It is fantastically themed for a "big boy" coaster. Right now they have a new dark ride under construction called Antarctica: Empire Of the Penguin. It utilizes the same trackless GPS guided tech that Disney used in Pooh's Honey Hunt in Tokyo.
And I disagree vehemently with most poster's here view of Universal Resort Orlando. I think that both of their parks are world class theme parks with many attractions that blow Disney's out of the water. In my opinion Islands of Adventure is the second best theme park in Orlando behind the MK. The Amazing Adventures of Spiderman and Harry Potter and the Forbidden Journey are the 2 of finest modern dark rides on the planet. The Curse of the Mummy is leagues better than Rock n Rollercoaster or Expedition Everest. Men in Black blows Buzz and Toy Story Midway Mania away as far as shooter rides go. Sure, Uni has some attractions that can be pretty lame, but so does Disney. But Disney gets a pass because, well, they're Disney.
This is NOT the most objective board when discussing non-Disney parks.