What is better for quick weight loss: treadmill or elliptical?

Both: Both treadmill and elliptical are about equal in the calories burned per hour of exercise, depending on the speed, elevation and resistance settings. The elliptical may be easier on the knees and hips; the treadmill better mimics running or walking. In my opinion, both are equal.

Depends: A treadmill will cost more due to higher manufacturing costs, the calories burnt between the machines is almost identical, the joint impact on a treadmill will be greater compared to a cross trainer and finally a cross trainer will be quieter compared to a treadmill. So there are the facts, you should analyze and then make up your own mind.