This is the stepmill by Stairmaster. Since the amount of vertical work you do is the biggest factor in energy expenditure, the stairmill is probably the best since you move your body more vertical feet per unit time than any other cardiovascular machine. This makes it very easy to work hard. You dont really even have to go fast because you are lifting your bodyweight the height of the stair with every step.
It might take you 10-12 steps to move your body upward that amount even on a very high incline with treadmill walking. The one thing you want to think about is training specificity. Yes, you will improve this energy system, but is it the best for you a hockey player?
I would think you should be doing as much on the ice as possible, because your cardiovascular system may become pretty strong, but the muscle action is very different, there is quite a bit of an isometric part of a hockey stride I believe, so do some stepmill but mix in the hockey of course.