Losing Weight
From my experience, the best machine for losing weight is the machine you like best. It is less about the machine and more about which one you enjoy using, the more you enjoy the more you will use it and the more you will lose. So if you love the treadmill then go for that one. If another machine floats your boat go for that one. Relatively speaking, the same intensity will burn the same calories, doesn't matter if its a bike, treadmill...