Out of these exercise machines (links included) which would give me a better overall workout?

i own a manual treadmill and a still walker and found that i lost more fat with the still walker. i was doing 30 mins on the treadmill 3-4 times a week until i got the still walker. then i ditched the treadmill and started doing 20 mins everyday whilst watching tv while dinner cooked and i lost so much more with the still walker. i found the still walker easier on my joints and feet. the treadmill would make my feet ache but seen as there was no impact with the ground on the still walker that wasnt a problem.