TTD is a one trick pony, and I've ridden it maybe 3 times in multiple trips to CP (MF, Maverick, and several others, I greatly prefer to TTD. . hell, I've even ridden Cedar Downs WAY more than TTD. . LOL. . and that's not even a coaster).
Kings Island is amazing, and think it's a better park than CP - especially for a non enthusiast, since they don't have as many "extreme" coasters as CP does. . and most of KI's coaster collection is mid-upper tier thrill, with don't' miss ones such as Orion, Beast, Diamondback, Bat, Banshee, and Mystic Timbers. I'd throw Adventure Express in there too. . a very fun (and fast) Mine train coaster. As well as some amazing flats including Boo Blasters on Boo Hill. .which is unlike any other version (think Disney Omnimover like Haunted Mansion, crossed with shooting dark ride).
If I had to choose? I'd go to KI. .. and yeah, no comparison between Mystic Timbers and any other coaster. . the trains are great (no wheel seats, so wherever you sit, it's smooth). . .love that one.