I actually didnt like Cedar point all that much, its still one of the better parks I have been too, but it was really dirty.. thats why I really dont like Cedar Fair or Six Flags parks.. bad theming, huge crowds and filth dampen the experience for me. I thought they had a handfull of good rides (Magnum XL, Raptor are the only REALLY good rides at the park).. and then they had a shit ton of crappy rollercoasters. Mantis is the best stand up rollercoaster I have ever been on, but thats not saying much because if I want to get kicked in the crotch for 3 minutes, Ill just go insult a linebacker (Ive rideen the Georgia Scorcher, Riddlers revenge, Mantis and some shitty batman ride in Houston).
I cant really limit it to one park, but Islands of Adventure, the two Bush Gardens parks, and Knoebel's would have ot be my favorite.. Knoebels is great because it feels like a park from the turn of the century still.. it doesnt have alot of rides, but what they do have there is great. the Bush Gardens parks are very similar in that respect they only have about 3-4 rollercoasters a piece, but what they do have shits all over anything at other parks... plus all of these parks are clean, very well spaced out, you never run into huge crowds outside of a line and the themeing is very good.
Islands of adventure isnt nearly as clean as I would like it, but the theming was really good, and dueling dragons kicks ass. If you havent heard about this its great.. its a hanging rollercoaster like Raptor or Alpeingeist.. but there are two of them, and their tracks are timed so it looks like you are going to smack the other one... and its really effective, I lifted my feat up several times
Note: being the huge dork that I am, me and a couple friends actually drove cross country after we graduated high school and went to about 50 different theme parks.. which wasnt that bad, because we bought season passes to Six Flags and Seaworld in San Antonio anyway so we got in free or cheap at a lot of places.