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

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I have an ultra 1 but it doesn’t have a dedicated triathlon so I went with a Garmin 965
Bought FR965 on sale for 450 2 weeks ago
Bro you can get a "used" (often actually still new in box) 955 on marketplace for like $300. The only complaint I have about mine is the barometer/elevation data is jacked up, but that doesn't seems to randomly occur with different garmin devices and isn't isolated to this one. The 965 is basically the 955 with OLED, which isn't a real upgrade to me. The 970 is marginally more advanced. But don't spend $500 on it, that would be crazy for a watch 2 generations behind.
I have a 965 and I charge it for like an hour a week whether it needs it or not.
Venu 2 plus and I currently use a FR965
I run in treadmills during winter, I have an Apple Watch Ultra and is way off. I prefer my 965 Forerunner for tracking even indoors. Actually I wear it all the time just because it's longer battery life.
I made the switch from AWU to Garmin. Cons: \- UI is frustrating until you get used to it. \- almost no 3rd party Apps, and even if the app exists is usually a very limited experience. Pros: \- Battery life is night and day \- Fitness tracking is fantastic \- Pairing with RayBan/oakley Meta is awesome Integration is 50/50, limited apple health integration. I'm really happy with my Garmin and not coming back to AW until they figure out how to deliver 1 week real battery life Instead of a refurb just get an older model, a 965 forerunner is great value.
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

Ranked #1
Oura - Oura Ring Series