I've used Polar for many years. I typically default to the simplest model with minimal features. My last one lasted a long, long time until the chest strap battery died, and I went looking for something new.

First attempt: a fitbit, one of the first ones to measure pulse ox on the wrist. It worked pretty well and had good battery life, but the firmware was buggy and it locked up regularly.

Currently I have a myzone MZ3. I love this thing. Like all things modern it connects to my phone with bluetooth, and uploads data to their website. It also connects to every club bike and treadmill I've used that support HR, it has ant+ and bluetooth. It also works with my old Polar wrist watch. It has enough memory to store a multi-hour hike, and download later.  I only have minor complaints:

1. They insist on using their own zone metrics, and display data as percentages based on those figures. I can download HR data as a CSV file, which adds a little extra effort.
2. The data on the website is averaged to 1 minute bins. When the phone app is uploading data, it reports ever 1-second interval. I'd like access to that finer-grained data. Not a deal killer, though.

ETA: it also pairs with my garmin GPS and records heart rate data during hikes, that data can be imported in google earth so it gives speed, position, elevation, and HR

Recently I got a garmin wrist unit with pulse ox, to supplement the data during times I'm not wearing the chest strap. It severely underreports HR above 120 BPM, and the pulse ox consistently underreports by 4 - 5 points when compared to my fingertip unit. It sits on my desk now and I rarely wear it.