My views on coasters and parks are quite different than most enthusiasts, so I'll just give an opinion of most enthusiasts about these parks that you'll probably agree with [:)]
Having been to both parks, I would say that CP is the better of the two. Its well kept, though the wooden coasters aren't maintained well (same with SFMM),has a nicer environment, and the coasters are more thrilling
(sorry, can't help but laugh at myself saying this as my opinion isn't very positive of these parks nor coasters). But I'd say go with CP definitely.
CP is also closer to a lot more parks, like Geauga Lake, and if you can head east of it approx. 5-6 hours make sure you go to Knoebels, it has 2 incredible wooden coasters, and IMO better than the stuff at CP and is a better park overall.