Now now, to answer this topic, let's make a distinction - I have no interest in the crappy little fairs that turn up in people's local parks, but if you go to a really good fair, it's far far superior to any theme park. That's why in a typical year I'll go to 4 or 5 German/Dutch fairs, and only 2 or 3 UK ones (one of those being Winter Wonderland, which is the UK's only German style fair).
If you're a fan of Ripsaw, for example, you clearly haven't ridden a Huss Top Spin at a fair, as you'll get a much much better ride - and let's not forget that the "Top Spin + fountain" idea did NOT start at CWoA, it started on the fairs (the travelling model uses water ballast to steady itself, which showmen quickly used to enhance the ride.
Likewise, anyone who rates Samurai highly needs to ride a Top Scan at full pelt. Extreme, for example, which usually attends Foire Du Trone in Paris, truly makes Samurai look like a kiddie ride. Same with Break Dances, I rode Alton's old Dynamo at Tilburg fair a year or 2 ago, and it was running at double the speed it ran at Alton.
And then there's the rides that you simple don't see at parks. My favourite rides of all time are all portable - Devil Rock (Huss Flic Flac), Airwolf (Mondial Inferno), Commander (Mondial Shake), and Frisbee (Huss Frisbee).
Not only that, they offer excellent catering - restaurants like Cafe Grell and Schwarzwald Christel offer far better meals than anything Alton offers, while the beer tents are legendary.
The problem is that in the UK, fairs have a bad reputation because, frankly, the majority of UK fairs are frankly rubbish. However, we do have some great rides - Top Buzz, Air, and 2Xtreme for example (Mondial Top Scan, Zierer Star Shape, and Mondial Capriolo respectively).
And anyway, for anyone who said nay to the original question, would you really turn down the chance to ride Olympia Looping?