IF I HAD TO PICK 1 CARDIO MACHINE...
It would be the AirDyne X from OctaneFitness.com. It's low-impact, space-efficient, easy to recover from, and works your whole body. Plus, there's simply no safer to way sweat and suffer, Ha!
I've tried a lot of fan bikes, but this is my favorite. It has the smoothest ride and the most versatility. Check out the companion videos to see what I mean.
Get 10% off my favorite total body fan bike from OctaneFitness.com, the AirDyne X (for heavier commercial use) or the AirDyne Pro, with my coupon code: