A year ago, I looked at what was available for activity monitors. DC Rainmaker has extensive reviews of activity trackers. The bottom line is that in the $100-150 range, the HRMs on the wrist bands are horrible!!!!! If you are considering a wrist based GPS, make sure to look at the battery lifetime with GPS on. I would think that you don't get as much battery life as you would with a phone (and you can buy an external USB battery for $30 to use with the phone). I have a Garmin Edge 500 for my bike, so I was looking for fitbit for walking, mainly. I decided on the fitbit one, finally. It is small and easy to wear. When I bike, I put it on my shoe, where it counts one step for each revolution. I checked against my cadence sensor and it was dead on accurate. Obviously the mileage is incorrect, but it does give you a calorie count. My friend has a fitbit one, too, and he the fitbit phone app to count calories and monitor is eating. If he eats too many calories early in the day, he will tough out the food later in the day. He has been doing a lot of hiking to lose weight (down to 250 from 300), but reached a plateau. By counting calories, he has been able to get down to 230, although the rate of weight loss is less than when lost the first 50 pounds.

I lost 30 pounds by increasing exercising (commuting 32 mile round trip to work four days a week) in addition to modifying eating habits. I had to learn that it is OK to not feel full! At lunch I had smaller (reasonable!) portions of food. Dinner consisted of a large salad (watch the dressing!) and some protein on most days. No desserts and watch the snacks. No food after dinner.

The fitbit one also seems to have decent reviews for sleep tracking. I find it to not work for me, as I can wake up in the middle of the night and if I don't move around, the fitbit does not recognize this as interrupted sleep. But I have never worn the fitbit in the recommended location for sleeping.

I look at it this way; accuracy is not as important as is looking at long term trends and relative numbers. While I have not investigated or tried any other apps, the fitbit one and Strava for riding (or even walks!) provide me with the necessary data for managing my fitness and weight.