Personally I like my Polar HRM strap and watch. I like to be able to track metrics like heart rate, but that is me. I've looked into some wearable options outside of the strap but haven't found anything I like better, or if I do the cost is prohibitive. Thinking about a blue tooth strap so I can ditch the watch - kettlebell lifting is hard on watches.

Good luck with your search. I've heard mixed reviews on the Fitbit from friends who have one, good luck with whatever you decide!