In a study published in the Journal of the American Medical Associatio ( Vol. 275 No. 18, pp. 1382-1450, May 8, 1996) treadmills are the best indoor equipment for fitness training.
The study compared treadmills, cross-country ski simulators, stair machines, rowing machines and exercise bikes. Participates were asked to use each piece of equipment at a perceived level of intensity. (IE: Easy, medium hard). Measurements were taken to see which piece of equipment caused the user to expend the most energy.
At a "hard" intensity the results were:
All pieces of exercise equipment burn 0 calories per hour if you don't use them however. So make sure that you enjoy the piece of equipment that you get. If you want to be able to read while you exercise then an upright exercise bike may be more suited for you then a treadmill or rowing machine.

In a study published in the Journal of the American Medical Associatio ( Vol. 275 No. 18, pp. 1382-1450, May 8, 1996) treadmills are the best indoor equipment for fitness training.
The study compared treadmills, cross-country ski simulators, stair machines, rowing machines and exercise bikes. Participates were asked to use each piece of equipment at a perceived level of intensity. (IE: Easy, medium hard). Measurements were taken to see which piece of equipment caused the user to expend the most energy.
At a "hard" intensity the results were:
All pieces of exercise equipment burn 0 calories per hour if you don't use them however. So make sure that you enjoy the piece of equipment that you get. If you want to be able to read while you exercise then an upright exercise bike may be more suited for you then a treadmill or rowing machine.
You did not mention the Treadclimber. I purchased a Bowflex treadclimber and I have had amazing results. But you were dead on when you said the results will be zero if you don't workout. Great information