Polar (the first company to make wireless heart rate monitors) is still the leader in the field. The Polar A3 heart-rate monitor is a favorite in reviews, which say it guides you like a personal trainer and allows you to view previous workout data. Reviews also say the Polar A3 heart-rate monitor is extremely accurate and easy to use, and its display is bold enough to see while you're working out. The only drawback to this brand is that you have to send the chest strap and wrist monitor back to Polar when batteries need replacing.
Polar's latest heart-rate monitor, the F11, also wins positive reviews among heart-rate monitors. For double the money, you get a lot of extra features over the Polar A3. Its "Keeps U Fit Workout Program" can be tailored to your personal goals, OwnZone keeps you in your target heart-rate zone, and OwnCal allows you to track calories consumed. (The less expensive Polar A3 heart-rate monitor does not have a calorie counter.) The Polar F11 uses a coded transmitter to detect your heart rate, eliminating interference from other nearby heart-rate monitors.
Best for beginners, the Acumen Eon Basix ES is easy to use and doesn't have a lot of extra functions to confuse novices. A top pick of Prevention magazine, the Acumen heart-rate monitor includes an in-zone goal countdown timer, an easy-to-set-up target zone function with audible and visual alarms, and a calorie counter. Unlike Polar heart-rate monitors, the batteries are user-replaceable, and the Acumen is water-resistant up to 30 meters. There's also a women's version, designed to fit a woman's smaller wrists and torso.
The Garmin Forerunner 301 is pricey, but that's because it has global positioning system (GPS) navigation ability, which tells you how far and how fast you're going. It can even give you directions home when you've finished your workout. The Garmin GPS heart-rate monitor also comes with PC-based software so you can analyze and create your workouts. It has a 14-hour rechargeable battery, sport-based heart-rate profile, and an AutoLearn function, which adjusts your heart rate zone as your fitness improves. Reviews say the Forerunner 301 heart-rate monitor is lightweight and easy to use. Like the Polar F11, the Garmin monitor uses coded transmission to eliminate interference. The Forerunner is not designed for continuous underwater use.