Personally I don't believe you need either. Neither will cause you to burn fat, or burn more fat, or the right kind of fat. They're just toys.
I have purchased all sorts of these toys over the years. The only thing they might do is keep me motivated to persist. But you only burn fat if you're in deficit caloric mode. Basically, don't eat as much as you burn. You don't really burn that many more calories while you exercise, unless you're maintaining a certain level of exertion for several hours. Your body has to use up the calories stored in your liver (about 2000) before it taps into the storage system (fat).
That doesn't mean we shouldn't exercise in order to lose weight. It certainly creates some calorie burn that wouldn't have occured if you didn't exercise. And the cardiovascular benefits are really very important. If you do any sort of weight training, you'll increase your lean body mass which will increase your BMR and you'll burn more calories while you're not exercising throughout the day.