Garmin
Forerunner 255 Series
Long battery; but wrist HR tracking is inconsistent.

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Switched from aw5 to Garmin epix gen2 standard - the batt life alone is enough of a win to not look back! Enjoy the Garmin bro!
I usually wear both a watch and a fitness tracker. For the watch, it is usually a Seiko SKX007 or a Citizen Eco-Drive Promaster. For the fitness tracker, I wore a Garmin Forerunner 245 for several years, and a few months ago, I purchased an Epix Pro Gen 2 Sapphire (47m).
Recently picked up a used Epix Pro Sapphire 47mm for $375,
Second the Epix Pro which can still be had (in white titanium) for $459. As someone pointed out, it has the same sensor as the Fenix 8 which the Fenix E does not share.
The deals are really good on new Epix Pros There are also some really good used deals and the occasional refurb. I'm happy with the one I have. If this is your first Garmin, its a really low price point to see whether you like the environment.
I had a Fenix 6 Pro Solar that recently bit the dust. I balked at the price of a similarly equipped Fenix 8 so bought an Epix 47 instead. Turns out I hated having an amoled screen. So I returned the Epix and bought an Instinct 3 with MIP. It’s a 45mm which I like so far.
1-2 gen old garmin fenix should be around that much new old stock, or see if you can find a refurb epix 2. I used an Apple Watch 4 before I got the epix 2. It’s fine for heart rate and mileage if that’s all you want. In fact any watch that has a hr monitor will be fine for basic training.
I initially bought the Epix Pro as my first Garmin watch, but I was disappointed with its performance. It felt like a device from a decade ago. I then returned and replaced it with the Fenix 8. If I had bought the Epix a year ago, I wouldn’t have upgrade it. However, as my first device, I think it’s fair to invest a little more in it. F8 47mm is more responsive 0.1 inch bigger screen with remarkably better resolution than same size epix pro gen2
Garmin
Forerunner 255 Series
Long battery; but wrist HR tracking is inconsistent.

Garmin
Forerunner 955 Series
Best value, clear MIP screen; limited smartwatch features.

Garmin
Fenix 7 Series
Durable, multi-week battery, flashlight; high price, buggy software.
Garmin
Instinct 2 Series
Rugged, solar multi-week battery; bulky, small screen readability issues.

Garmin
Enduro 3
Multi-week solar battery, lightweight; but bulky form factor.

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Oura - Oura Ring Series

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Apple - Ultra Series

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Garmin - Enduro 3

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Garmin - Fenix 7 Series

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Garmin - Forerunner 255 Series

Ranked #1
Oura - Oura Ring Series