Garmin
Forerunner 255 Series
Long battery, but wrist HR often inaccurate.

Running these analyses costs money. Buy through my links to help keep lights on! I may get a small commission.
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
Garmin forrunner are top notch. They have several models depending what you all want/need beyond swim but all work great in and out of a pool. Done several Ironmans (and the training for them) with them with spot on accuracy.
I have the 920 which is old now but works. Pool accuracy is due to the swimmer. Since it can’t use GPS it uses a motion sensor and registers a lap based on the wall acceleration followed by a stroke. It doesn’t typically pick up kick board laps for example. Also may not work perfect if your doing breaststroke. However a flat freestyle workout it should work without issue
Garmin
Forerunner 255 Series
Long battery, but wrist HR often inaccurate.

Garmin
Forerunner 955 Series
Endurance battery, value king, but clunky UI.

Garmin
Fenix 7 Series
Rugged, long battery, maps, but HR and software can struggle.

Garmin
Enduro 3
Unrivaled multi-week battery, solar-charged, but bulky.

Garmin
Forerunner 965
Lightweight, vibrant AMOLED, maps, but wrist HR and swim issues.

Ranked #1
Oura - Oura Ring Series

Ranked #1
Apple - Ultra Series

Ranked #1
Garmin - Fenix 7 Series

Ranked #1
Garmin - Fenix 7 Series

Ranked #1
Garmin - Forerunner 255 Series

Ranked #1
Oura - Oura Ring Series