Air. Hold your fire!
I think I've said this before, but anyways...
Nemesis, Oblivion and Air are all brilliant rides (in my opinion) they were all firsts, and they were a novel concept at the time. Because of the diversity of the rides, you just can't compare them against each other. Nemesis offers a fast and furious ride, Oblivion offers a sudden shock and Air is simply exhilarating.
The reason I prefer Air is because it offers an exhilerating experience. Something doesn't have to be thrilling to be a crowd pleaser, in fact, on my trip to Alton Towers with my friends, 3 out of the 5 of us prefered Air over any roller-coaster there simply because of how fun and exhilerating it was.
It hurts my neck though.
And it sucks when you get stuck on the lift in the pouring rain.