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

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Garmin 920XT 😅 Stil going strong 🤷♂️
I have an ancient Garmin 920XT (I've beat the hell out of the watch and for $450 in 2014 with HR strap) it keeps on keeping on. Just back from Biking the Balkans and it gave me more data than I can use.
What keeps me with Garmin, and why did I return to it? battery life. the fact that I can look at my dexcom data not only on the watch face, but also add it to the activity screens, which is incredibly important and useful for cycling, working out, hiking, or just about anything that I do. (NB: cannot add Dexcom complication to Apple Watch activity screens, which is so patently stupid. If it can be added onto (only a few) faces, why not elsewhere? ) it’s relatively easy to customize the watch and screens, and create activities relevant to me. the menus have improved and are a bit easier to navigate. The watches are long lasting and durable. I expect many years out the 970 based upon my experiences with the 920xt. plethora of statistics and data are there if you want them. Niggles: the cost. They are pricey. Plus they really dumb down the lower models, like the venu, trying really hard to upsell you. the watch iq Face It app- why is there yet another app for this? Stupid. Also, ostensibly the face it app enables one to create a custom face. Yet, so many complications are missing. Why? So stupid and lazy. I am sure that is a commercial decision - they want people to buy the faces rather than allow folks to make their own. subscription? GTFO. (I don’t bother).
When I started out, I picked up a used Garmin Forerunner 920XT from eBay. It worked great for me for years, and I passed it off to a sibling who says it's still going strong. It's a little basic by modern tech standards, but it's easy to read when running and the GPS tracking is good. It works with Garmin Connect, so you get all the tracking functions for a triathlon watch that you would with any other Garmin, but I found I couldn't add other apps to it - Garmin Golf, for example. A used one right now will probably cost about $120US, including shipping. 3 years ago, I saw a deal on Amazon Prime Day that I had to go for, and picked up a Garmin Forerunner 945 for essentially half price. I love it. It's done everything I've asked of it and more. Battery life is brilliant - I went on a week long vacation and forgot my charger. The watch only ran out of juice when I was at baggage claim after the flight home. I've added multiple apps to it - golf, workout, etc. - there's a lot of functionality to it now. Yeah, it's not cheap, but if you're able to spend the money, I recommend it.
I've had my forerunner 920xt for 10 years and its still OK to use just have replaced strap a number of times
Part of the "use it til it dies" club. I'm still rocking my Garmin 920 XT triathlon watch from 2015..... which may be one of the oldest in this thread?? Works fine, even though I only use it for running these days.
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