Count me in the minority, I don't like Knott's, Universal, or Six Flags. I live in San Diego and have passes to Sea World and Disneyland. We use Sea World passes as a back up when we can't make the trip to Disneyland or when the weather is too hot at Disneyland, also on overly crowded days. We don't go to Sea World to ride the rides though, we go for the shows and animals, it's like a glorified zoo to us. We used to have passes to the San Diego Zoo, but the hills in the park were just too much for me as I am disabled.
I have been to Knott's a number of times. Knott's is a great theme park. I love the theming, I enjoy the atmosphere, but the rides are very limited at Knott's for people like us. My boyfriend and I do not ride roller coasters, or rides where you get wet, I don't like swinging rides and he doesn't like spinning rides. Knott's truly has separate kids rides and adult rides, Disneyland does not. At Disneyland, we can ride every ride in Fantasyland, quite happily, and Casey Jr Circus train is one of our favorites, in addition to It's A Small World. At Knott's, at last count (in early January) there were only six rides that we would ride. Unfortunately, six rides is not enough to justify the cost of going to Knott's Berry Farm for us.
Universal Studios California to us was extremely lame. Sometimes I wonder where they come up with the ideas for theme parks. The movie theme is there of course, but it just doesn't grab you and immerse you into a park with all one theme like Disneyland does. The last time I was at Universal Studios I left thinking "that's it". It's also more of a "half day" theme park to me, whereas you can spend a full day at Disneyland.
Six Flags is the worst of the theme parks from where we stand, and it's not just because we don't like roller coasters. The atmosphere there is very "high school" and it is always overrun with rowdy teenagers racing from one end of the park to the next. There is a lot of trash on the ground, there is a lot of maintenance that needs done that isn't done, and there are a lot of things that you notice that destroy the magic of the place. The other big gripe about Six Flags is that they want you to pay for the fast pass system (Flash Pass if I remember correctly). If Disney's is free, why should I pay almost as much as my ticket price to use it? I understand it's optional, but seriously, it just seems to silly to pay that much. I would rather them raise the prices and just include the Flash Pass in the ticket prices.
When I think about how much more there is for us to do at Disneyland, and I look at the prices of the other theme parks $80 for Universal, $59.99 for Knotts, and $64.99 for Six Flags, we always think for a little bit more we can have Disney so why go anywhere else. And I know you can get discounted tickets online, but we are last minute people when I am feeling well enough to make a trip, and so we very rarely can "plan ahead" for things like a day trip to a theme park.
Sea World is actually becoming too overpriced, but two years ago we scored a deal of $99.00 for Silver Passports that included parking for 2 years. They expire this summer on my boyfriend's birthday and they are almost double the price now. We are still trying to decide if it's worth it to renew it. We do use them frequently during the summer, at Halloween, at Christmas, and on New Year's Eve.