Features that count

Display

A good display will have easy-to-use controls and will show some combination of your heart rate, calories burned, speed, resistance levels, and details such as time and distance.

Adjustability

Look for machines with programs that allow you to adjust routines based on your fitness level and have heart-rate-controlled workouts that consider your age, weight, and gender.

Heart-rate monitor

Those with a chest-strap heart-rate monitor are best because they don't impede your movement. Contact monitors measure your heart rate only when you're holding onto them, which can impede your natural stride. But it doesn't need to be a deal-breaker; stand-alone heart-rate monitors are available for about $28 to $100.

Resistance

You'll also want a machine that is easy to adjust and has a variety of workout levels. Look for an elliptical exerciser that has a range of resistance that fits your workout needs.