Garmin
Forerunner 255 Series
Long battery; but wrist HR tracking is inconsistent.
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I don't think you'd want to go with mine. It's a [Forrunner 735XT](https://www.garmin.com/en-US/p/541225/), which is an older model that's been discontinued. You could probably find it used, and it's certainly a solid watch, but the technology has improved drastically in the years since I bought it.
Wahoo Element Bolt for road cycling, Garmin Edge 520 for MTB, Garmin Forerunner 735XT for Triathlon and Apple Watch Series 10 for everything else. Have a hate relationship with my Garmin devices (which is why I got the Bolt when my 520 decided that properly recording altitude data was not in its best interest), but who’s to say that they don’t go after Wahoo next for some idiotic reason?
Mine finally gave out a few weeks ago. I just got a fenix 8 47mm amoled. I had the 735xt for 7 years and the screen started to flicker during activities and it’s now unusable.
I liked the simplicity of the 735xt. I didn't really feel it on my wrist, it was light, and didn't get in the way. The fenix 8 is a very different watch. It's much larger and heavier and I find that I think about it more often, which i don't like. I do really like the additional features that the fenix has, like the sleep tracking and hrv measurements.
My almost 10 year old Forerunner 735XT lasts longer than that, even if I keep it on during showers and record my commute to work and back every day. Newer, more powerful Garmin watches, like the Enduro 3 or Instinct 3, are even more impressive.
I think many people on Reddit are just too negative about it. Software bugs are obviously annoying, but even my FR735XT still gets Firmware updates every now and then, so it probably is still getting better. And who the f* actually needs LTE and/or Satellite calls on a watch? That's what you bring your phone for and even on my phone I don't need LTE or Sattelite calls.
The difference won't be that big probably. Up until last week I ran with a 10ish year old Forerunner 735XT and it was still super capable with easy ~1week+ of battery life.
Had a forerunner 735xt since 2018, sadly it died 2 months ago but i was honestly thinking of going instinct 3, as it is 100 dollaridoos cheaper
I had a $20 vivo active 2 that was super simple. Wanted heart rate so I got a cheap Fitbit. Wanted better tracking and ability to use chest strap heart monitor, so i got a used forerunner 735xt. Fitbit wanted a subscription to see most of the data. Garmin cost more but didn't require subscription. It worked good enough but was aged technology. Got a good deal on a used 955($200 used). It's a MIP screen and I order it over newer OLED screens.
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

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Garmin - Forerunner 255 Series

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Oura - Oura Ring Series