I have been to a lot of parks. Some have themed areas, while other's like Cedar Point are just good old fashion ride parks.
So, I would have to say that Cedar Point (Sandusky Ohio) is one of my favorite parks, mainly for it's large selection of roller coasters and rides. Total coast for one person to get in is around $60.00 but there are all kinds of admission policies there. The Water park Soak City still requires it's own admisson, but you can buy a combo pass that inludes both parks.
My favorite theme park would have to be Six Flags Great America. (Gurnee, Illinois) They have a great selection of rides, and some pretty decent coasters. They also added a large water park to the property in recent years and doubled it's size, and, it is very cool that the water park is included in your admission to the park. But, Great America is very pricey, what you don't pay for in admission, they sock it to you on everything else, like parking the car, and lockers. I have also found the food at Great America to be expensive and cold.
Other than that, the Florida parks, Disney, Universal, Sea world, and Busch Gardens are at the top of the park food chain, they are the most lavish, and beautiful. But, they also come with huge crowds, and whopping entrance fees at around $80.00 just to get in. However, when it comes to entertainment value, they give you your money's worth.
Some parks charge way more than what they are worth, like Michigan's Adventure (near Muskegon Michigan). Cheap admisson, while picking your pocket on everything else, and offering nothing but rides and expensive food. They do have a nice water park, but, only 5 decent rides in the entire park. $25.00 admission, but, plan on spending around $50-60 per person if you intend to buy food or rent a locker for the water park.
Another interesting park is Indiana beach, But, that has been priced through the roof. Used to be around $14.00 they added like 2 new rides over a decade, and it now cast $39.00 for a ride wristband. The cool thing is, a good majority of the park sits on top of the water.