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

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Samsung Galaxy Watch 2018. Still working fine.
Sleep tracking worked on my original Galaxy Watch back in 2019 than my Apple Watch 11 haha
my galaxy watch 1 is still working fine since 2018. I'm planning to retire it this year.
I can't comment on Garmin watches, but does he already have an iWatch or a Samsung Galaxy watch? I track all my rides with my Galaxy watch with the strava app on it. Just food for thought. When I was looking at Garmin I was lookin at the Fenix models.
I am using Samsung Galaxy Watch that syncs with my Samsung Galaxy phone
I wore my galaxy watch for 3 years climbing with no protection on it and while it got some scratches, it never really got anything on the screen and nothing cracked, it's a pretty durable piece of hardware. The only time it really got in the way of climbing was on the occasional very large sloper where you get an arm on the hold and on crack climbs. I don't wear it anymore because I no longer enjoy smart watches in general, but it was a pretty solid piece of tech in terms of durability.
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.

Ranked #1
Oura - Oura Ring Series

Ranked #1
Apple - Ultra Series

Ranked #1
Garmin - Enduro 3

Ranked #1
Garmin - Fenix 7 Series

Ranked #1
Garmin - Forerunner 255 Series

Ranked #1
Oura - Oura Ring Series