I have never used a Polar HRM. I have a MIO wristwatch HRM and a Sigma BC-2006 with HRM chest strap. The MIO gives crazy high readings or no readings when my wrist is dry. The Sigma needs my chest to be moistened before I begin, but works well after it once starts. I did not buy a Polar because I read that the battery in the chest strap cannot be replaced by the owner. It seems there are plenty of users who have a strong allegiance to Polar products, though (judging by previous threads on HRMs).