All of them. ;-) The thing is that all three offer a different challenge and are quite different in style. Personally, I recommend 2097/XL, but you better have a look at "which do you like best"-discussions from recent years.

I couldn't agree more with Lance: It is amazing to see how lap and race records can still be improved significantly after so many years. Personally, I come back all previous WipEout games every once in a while and have a go at some of my times. In terms of the joy, the challenge and the longevity of finding that perfect lap, that perfect race you simply don't need barrel rolls - likings and dislikings of this new mechanic aside.

Ben