While there are other very good HRM brands, an advantage of Polar is that many gyms have cardio equipment that reads a Polar. So if you have your chest band on, you can read you heart rate on the equipment display rather than trying to check your wrist.
An advantage of non-Polar HRM's is that they seem to pick up less interference from other HRM's. I used DH's Polar in spin classes because it had a backlight but it would get some misreads. Like a heart rate of 200 while warming up, & then a HR of 50 during intervals. DH used to get some pretty high readings as we coasted down a hill past the med school when we lived on a college campus.
But honestly, Polar is still the gold standard.
Debra