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

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Garmin Forerunner 935 was going strong and was about to hit the 5 year point... until I did the stupid thing of freediving with it.
Forerunner 935, had to wear my friends enduro for my one 100 miler though but it just about sees me through 100k
Fenix 8 47mm Sapphire. I've had a range of Garmins (Forerunner range: 35, 235, 935, 945, 955) but the 970 didn't appeal to me (accent colour on side and domed glass) so I got my first Fenix and first AMOLED watch (solar was thicker than my 955 which was already a bit thick under clothing). Love the look of the Fenix a lot more, plus better battery life
My 2019 Garmin Forerunner 935 is still going strong.
Ahhh I miss my forerunner 935 with its 2 week battery life, those were the days, this ultra 2 is not hateful though. Garmin does make a decent outdoor activity watch though.
In the words of Eddie Merckx: don’t ride upgrades, ride up grades. It applies to running as well - the benefits of a piece of gear are far far outweighed by training itself. If you want to focus more on training maybe you need more structure, different workouts, different diet, periodization through different blocks, etc - none of which a different watch will help you achieve. I would say getting a heart rate strap that works with your current watch so you can track that accurately would be a better purchase for an upgrade in gear. Also make sure you have really quality shoes. Your money is definitely well spent keeping your shoes relatively fresh as they will lower discomfort and avoid injury if not worn out. I LOVE my Garmin Forerunner 935 and highly recommend the brand but it’s not going to give you much you aren’t already getting from the Apple.
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

Ranked #1
Garmin - Forerunner 255 Series

Ranked #1
Oura - Oura Ring Series