Forerunner 910XT

I have a Garmin 945 that's going on 6 years, following a Garmin 910 that still worked when I retired it after 9 years. Right now the battery lasts ~6 days, down from ~2 weeks when I bought it. One button is starting to have intermittent contact issues.  On the water front, these are triathlon watches and are designed for swimming.  I have replaced each band once, and I use a quick-release leather band for daily wear and a quick-release silicon band for swimming.  My next one will probably be either the 955 or 970, once the button gives out.

Was GARMIN for many years, starting with Forerunner 910XT and progressing to Fenix 5Pro Saphire. Did last Tri event in 2019 and ended up switching to AWU when it first was released. I have no regrets, if I ever go back to Tri will probably use another GARMIN for racing/training but keep AWU as daily driver.

You buy a Garmin for what it does today, not for what it may or may not do in a year with some maybe-happening update. As opposed to typical (real?) smart watches, a Garmin will keep working for years and will be compatible with the app even if it is not receiving further updates to its software. I can go for a run with my 15 year old 910XT today stick the ANT stick on my computer and upload all the data to the app with all the functionality the watch had the day I got it. I can probably do that even with my 18 year old 305 (I haven't tried in a while, but I would expect it to work). So, buy something that satisfies your needs today. It will keep doing it's job for its lifetime. If you develop additional needs, well then you can consider an upgrade.

You won't get "very accurate hr sensor" in any watch, they all use the same technology which has its own disadvantages. As long as I'm aware you can't program strength directly on any garmin watch.  Your best bet would be older fenix/epic/forerunner series 9

If you want maps, it's the 900-series.