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

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Disable GSP, Bluetooth, HR, etc or buy a watch that is specific for ultra and adventure racing. You can find an older Garmin model with ultratrac for a reasonable amount if you’re not looking to break the bank.
I have an epic pro but definitely would have got the gen 3 for everyday at work if they put the new sensor in it. Crazy to me they didn’t.
I’ve had both and definitely have had more issues with Garmin. I have yet to experience a mid activity crash on my AWU in over a year, something that I’ve had happened multiple times on every Garmin device I have ever owned (a lot, I started with a FR 205 or 305). I still own a Garmin edge and it happened again last week. Riding along and you look down and the screen is just shut off. I do miss the battery life of my old Fenix but I got used to putting the AWU on the charger every time I shower and that seems to work 99% of the time. I don’t see a bright future for Garmin. There’s companies like Coros that make arguably better watches now for a fraction of the price (don’t take my word, look at all the pros using Coros now). When my Edge dies I’ll probably switch brands.
I switched from a Garmin Fenix to an Ultra 2 and I’m never going back to Garmin. Most of your peeves can easily be remedied by going in the Watch app on your phone and setting up what you want to allow to show up on your watch as notifications. It’s 100 times more fine grained than what Garmin does (pretty much all or nothing). Not that it’s Garmin’s fault, they just don’t have access to the OS on your phone the way Apple does. I was overwhelmed at first but quickly turned off notifications for all but a few apps. Now, if you want something more focused on sports then you’ll be better served with Garmin, although Apple’s Ultra variant is no slouch either, especially paired with an app like WorkOutdoors. If you’re going to go that route I would take a serious look at Coros though, they make arguably better watches for much cheaper in my opinion.
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.
Sapphire screen on a Fenix, or the instinct 3 tactical given the ruggedness of his future work.
Having gone through many Edge and watch products, get the Epix or Fenix with Sapphire glass. No scratches, great visibility, long lasting battery
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