Wingate. You can set it so where you have to achieve a certain RPM before the weight/resistance rapidly increases and then it's just an all out war. It is very hard to duplicate with any other modality, but you CANNOT cheat or mail it in. That said, they are stupid expensive. So when money is a concern, airdyne > prowler because you can do it inside so weather is not a deterrent. That said, I like the prowler a whole lot too for active recovery and training "legs" when someone's back is jacked up.