Six Flags sucks, you will see virtually no coaster enthusiast older than 30 defend them. It is absolutely the wrong comparison to make. The only Six Flags park I would consider going to currently is Six Flags Fiesta Texas, and even then it’s low on the list. Cedar Fair parks range from tollerable to quite nice, they aren’t immersive (outside of Ghost Town at Knotts) but deliver on thrills. Busch Gardens, Dollywood, Silver Dollar City are a big step up and tend to strattle the theme park/thrill park void incredibly well. If a Disney enthusiast wants to dip their toe outside of Disney Busch Gardens Williamsburg, Dollywood or SDC would be my top suggestions if they can’t stomach going to Universal. Speaking of “the dark side” it is clear that Universal turned over a new leaf after F&F Supercharged failed spectacularly. Epic Universe looks stunning, and appears to be a park with Harry Potter detail in every one of its lands.
For a completely different experience, and one I also enjoy, there are some really great independent amusement parks that have charm but provide an old school escape of yesteryear where the amusement park was a city park on steroids. Places like Canobie Lake in Salem, NH, Kennywood outside of Pittsburgh, Knobels in Elysburg, PA. They are good times in their own right I appreciate. Then there are places like Holiday World in Santa Claus IN, that while there is a light theme, provide a much closer experience to the amusement parks I just listed as opposed to Disney but is still incredibly charming.