Because I'm the editor of Engadget by day and a volunteer coach in my free time, I often get asked which GPS watch or fitness tracker to buy. (People also ask what I'm wearing and the answer is: All of them. I am testing all of them.) For my part, the best running watches are quick to lock in a GPS signal, offer accurate distance and pace tracking, last a long time on a charge, are comfortable to wear and easy to use.