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

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I just upgraded to the galaxy watch 7 (just set it up it minutes ago) 40mm and the Watch 4 classic looks better and the rotating bezel protects the screen. I'm a little scared to break or scratch the glass of the 7. But it's quicker indeed, and lighter but let's see if battery life is better, I don't use the screen always on but was having bad battery life on my aged watch 4, that wad the main reason. I considered the OnePlus Watch 3 for its great battery life but since I own a Samsung s24 ultra decided to buy a used 7 for 81 euros.
I just upgraded to the galaxy watch 7 (just set it up it minutes ago) 40mm and the Watch 4 classic looks better and the rotating bezel protects the screen. I'm a little scared to break or scratch the glass of the 7. But it's quicker indeed, and lighter but let's see if battery life is better, I don't use the screen always on but was having bad battery life on my aged watch 4, that wad the main reason. I considered the OnePlus Watch 3 for its great battery life but since I own a Samsung s24 ultra decided to buy a used 7 for 81 euros.
The "no- phone" condition is what made me buy a lte smart watch. I own a samsung galaxy watch 4 classic lte for years and it serves the purpose very well. If you're buying now it sold be galaxy watch 7 lte which is on sale for ~13k in republic day sale. On the apple side i would suggest SE3 lte. FYI my owns a SE2 lte.
I use a Samsung Galaxy 4 Classic. I've had it for a couple of years. It replaced a fitbit, the one that looked more like a watch. I do not have a Samsung phone. Pros: it looks like a watch. I got a metal band and it really could pass for a real watch. It's snappy and useful. Voice commands work. Notifications are good. Dial is useful for volume control. Battery life is good. One day. Beyond that it's questionable. I once forgot my charger and got almost 2 days on it by running it as only a watch. Cons: Wallet requires a code to unlock which I don't like. So I don't use it. It's a Samsung and I don't have a Samsung phone, so I miss some nice to haves. It won't stay on apps and goes back to the home screen. Annoying when I'm working out and it doesn't stay on my fitness screen. Seems kind of dumb. Overall I'm very pleased.
I did the same, bought a refurbished 6 classic from Amazon. Been very pleased with it coming from the 4 classic
I upgraded to the 8 classic from the 4 classic. I prefer the classic because of the looks and the rotating bezel. The main upgrades I noticed: 1. Much faster. 2. Battery life is significantly better. 3. No need to touch the screen to start navigating. 4. 4 times the memory. 5. Will get software updates for many years, unlike the 4 classic that will no longer get updates.
Swapped my Galaxy Watch 4 Classic (they were 3-4 years old and battery is totally dead) for OnePlus Watch 3 about a month ago and really happy with them. 3 full days of battery life (AOD, pulse tracking, glucose monitoring widget on), charges really fast, nice size and feel on the wrist. Sleep tracking seems accurate enough too (although I don't really know what to do with the data). Was actually thinking about getting PW4, but they are more expensive and battery life is not as good as OPW3.
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.

Ranked #1
Oura - Oura Ring Series

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Apple - Ultra Series

Ranked #1
Garmin - Enduro 3

Ranked #1
Garmin - Fenix 7 Series

Ranked #1
Garmin - Forerunner 255 Series

Ranked #1
Oura - Oura Ring Series