I've had a huge number of different heart rate monitors over the years. I still have my very first chest bands made by Polar and Suunto. These needed a proprietary watch and then the batteries would die and they are not user replaceable so you have to send them off.
In the last five years, I've been using a variety of devices, the best has been the Scosche Rhythm Plus. This I bought five years ago and have two of them. They are optical and just fit on your upper arm and seem very accurate. But just last week, I discovered that I had lost one of them (ok, not lost, it is in a bag somewhere) and I couldn't find the other (it turns out it, was under a chair). So time to get at least two of these things. The main thing about the wrist band or a watch is that it is just so much easier to put it on than a chest strap (no matter what I always forget to throw it on and then you are untucking your shirt and things to get it placed correctly. An arm band is nice in that it doesn't constrict anything.
So off to look at some reviews and not surprisingly I found a bunch of what I would call light reviews like PC Magazine and then a deep look at the Amazon reviews and of course really analytic reviews from DC Rainmaker:
- At least for chest straps, DC Rainmaker reports they are all essentially identical in terms of performance and are all super accurate and the OH1 is the most sensitive on the market (although the Whoope is apparently nearly always way off)
- Apple Watch 6 and not the SE. If you don't need Bluetooth or ANT+ connection to your Power Meter or to your trainer, then the Apple Watch in workout mode does a very decent job of recording your heart rate. I find that I use my Apple Watch for hikes and things, but if I'm doing dedicated cycling, then an arm band with those outputs is basically essential. The Series 6 and later are quite good, but the SE isn't the most accurate for heart rate or for GPS tracking.
- Polar OH1 (DC Rainmaker review) and now the Polar Verity Sense. This is an armband watch that PC Magazine really likes. The Polar OH1 is on sale now at $68 and has both ANT+ and Bluetooth. The Polar Verity Sense at $90 has a few improvements for $90 at Amazon notably the 20-hour battery life, dual channel concurrent ANT+ to connect to two devices and the range increase to 150m (so you can watch heart rate while playing soccer). You can also use it for swimming now as well plus it is supposed to fit better. This is the same optical sensor as the Polar OH1 so net, net, if you don't need the swimming and battery life, the discounted Polar OH1 is a nice deal particularly if you don't plan on swimming with it (I do!)
- Scosche Rhythm24. This is the successor to my Scosche Rhythm Plus which everyone (including me!) has loved because it's accurate and it has dual ANT+/Bluetooth Smart. The main difference is moving from a 2012 MCU to a 2018 processor from Valencell. That is what has moved battery life from 6 hours to 24 hours. It also has more than one LED so you can tell the charge level which is pretty handy. It also has HRV built in and it will also let you swim which is nice. They also have an NFC-A tag so that when you get close to a treadmill, it senses it. All of this for $60 at Amazon, so a bargain It is decently accurate but not as good as the Polar OH1 (or Polar Verity Sense). It is loaded with lots more metrics than the Verity Sense including Run Pace and Cadence, Cycling Cadence (if you stick it on your leg, although I don't need this given the power meters I have), at rest HRV plus it displays HR Zones. Although Amazon reviews have said the Rhythm24 is not that reliable.
Net, net, with the current pricing, the Rhythm24 is a real winner, it has the same performance as the Polar Verity Sense and has lots of additional data as well, but the main thing is that from the $100 list it is down to $60 so a real winner. I'll probably try the Rhythm24 and return the Polar Verity given the pricing differences.