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

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I picked up a used 6 classic and it turned out to be amazing. I was really surprised by the battery life of it as well as the fitness features are also very good. And also tinkering with adb lol It gives me approx 1.5 days on a full charge. I started at 8 am (100%) to 11 pm (30% left) and slept with it and woke up next day with about 16% battery. (All without using any apps except the health app, calls, maps and AOD all the time)
The sleep tracking is so good bro. I would say all the health related features are better than apple watch, for me. But the overall ui of 6 classic is not so smooth because it's old ig (recently switched from apple) And I've been installing apps like yt, instagram and Reddit. They work but not so great.
A scraped up Samsung Galaxy Watch 6 classic so I can keep up my steps, blood sugar and have a nice homage to Tom Clancy's the Division when I wake up
Most recently had had galaxy watch 6 classic 43mm, watch 7 44mm, and watch 8 40mm, all great watches . Wanted to go back to pixel watch since all the improvements so I sold my watch 7 and got the pixel watch 4 45mm.. it's my favorite of them all now. Great display and battery life is the best out of them all.
The battery still improves, as I told you, it is not a gigantic change, I had the watch 4 and I went to the 6 and I easily went from about 20 hours of the watch 4 to a day and a half, almost 2 days using the watch 6 classic, here I give an example of. For headphones you could also consider looking at options from other manufacturers, I understand the "galaxy ecosystem" thing because I am also a big fan of it, but I don't see that consideration as bad https://preview.redd.it/xdu60542s4vf1.jpeg?width=1440&format=pjpg&auto=webp&s=e3151ba6d97dbbf0f7fecb29bd709655cd016af9
Not true that Wear OS can't work with iOS. There are no official apps, but Bridge and Rulia Sync (search this reddit) both work well for notifications NFC payments (via Google pay), GPS (offline map apps only) can also work standalone on the watch As for other functions, including replying to messages ... any apps that require internet are probably not functioning right now, as iOS cannot transfer internet to Wear OS I have a Galaxy watch 6 classic and notifications GPS all work fine when paired with iOS
I still use my Galaxy watch 6 classic, no real issues here. Might try and get someone to upgrade me for Christmas.
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