Good treadmills are eays to use, have ample space to support all heights, and come with a wide variety of workput programs to suit all levels of fitness needs. A treadmill has at least a 55-inch deck (as most of us are 6 feet and below) and support a weight of 300-325 pounds.
Buying a treadmill simply depends upon your habits. Don't waste money on an expensive traedmill if you are lazy / have no time to walk / run. It is as basic as that.
The thing to know about treadmill running: Research shows that running on a treadmill requires less effort than on a sidewalk or a trail. Moreover, a study published in 1996 says that that running on a treadmill at a 7-minute-mile pace and a 1-percent incline is equivalent to running outdoors.
The best treadmill: ProForm 505 CST (10 mph spped, uotp 10 % incline, simple display, 18 interval programs)
The second best treadmill: Gold’s Gym Trainer 720 (LED screen)
The best treadmill upgrade: NordicTrack c990 (touchscreen, for taller people, 60-inch deck, hydraulic lift for easy folding)