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

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I got a vivomove sport. I will say I wish I got it in black instead of white because the white just inherently looks a bit more cheap/you have a harder time finding straps that match and stay clean. But it has traditional hands and doesn't have a digital display til you tap it and I like that. (Plus Garmin has a good track record for smartwatches in general.)
To be honest, I have not looked at the sleep tracking (not something I'm interested in). I've had no trouble with the all-day comfort, even with a slightly bulkier leather-looking 'classic' watchstrap.
I literally can’t live without smartwatch, I’d miss 2/3 of the work calls/msgs, waking up with the smooth vibration instead of a loud alarm makes my mornings so much better (not good lmao, but better) and the sleep monitoring is crucial to me, as I can see better how I’m managing my time and how to fix potential sleep deprivation. I hate screens tho, so a square on my wrist would make me go crazy ahahah so I opted for a garmin vivomove sport, which is a cool hybrid, gives me what I need keeping a nice and clean design.
Garmin Vivomove Sport, because hybrid rokz!
The Forerunner 55 is a great, basic watch. If all you're looking for is sleep, heart rate, steps, and some other basic stuff--plus a better aesthetic--check out the [Garmin vívomove® Sport](https://www.garmin.com/en-US/p/742133/pn/010-02566-00/#specs).
For awhile I wore a Garmin Vivomove as my main watch for this reason. It had everything I needed except GPS - I was running without my phone at that time because I didn't want to carry it, so I'd switch out to my older, but GPS-enabled, Garmin on runs. Now I run with my phone so a Vivomove would be fine (you can enable your phone's GPS to work with it). Mine looked very much like this one. They have a lot of different colorways. I only stopped wearing it because the early Vivomoves (like, 3rd gen.) had screens that died after two years. I'm sure that's been addressed by now. https://preview.redd.it/7j1ktwiglkdg1.png?width=362&format=png&auto=webp&s=a36d7e96414ae598d28e814fc203086b27d0a538
A lot depends on what you want out of it - but would also say that I think you probably aren't female based on your profile (but could be wrong) in which case would drop the Lily 2 variants (if want a hybrid then the instinct crossover is much more masculine and offers a lot more than the lily or could look at the vivomove series). Would also scratch the vivosmart as old and missing loads of features the others currently offer -and would say the same about the FR55. Would probably also drop out the inspire 3 due to its more basic nature (more a health/fitness tracker than smartwatch - technically so is the charge 6 but does offer more along smarwatch lines than tracker lines so fine to consider it more of smartwatch than tracker). And again would skip the FR945lte (as old, plus lte only usable for live track functionality - if you want lte for garmin then fenix 8 pro is the only garmin option --- none for fitbit unless you have an android phone and then get the pixel watch 3 or 4 lte versions). Do you want to make take/calls - then fitbit sense / vera; and garmin venu 3 / 4 / x1; fenix 8 series (and its variants) and FR570 and FR970 Do you want nfc pay - fitbit uses google wallet / garmin uses garmin pay and isn't as well supported as google wallet - but check on garmin pay support site to confirm what banks/financial services support it in your country (in most there is usually 1 digital financial service that is quick, easy and free to set up and use i.e. Curve/Revolt in most of Europe if you normal bank isn't supported. Do you want offline music as only the garmin's offer - fitbit doesn't. Do you want offline maps - Venu x1, fenix 7 (not worth it unless significantly cheaper than F7P - note that the epix 2 is the amoled version of the fenix 7), fenix 7 pro (not worth it unless significantly cheaper than F8), F8 variants; FR970 (and its prior gen FR965 (amoled) or FR955 (mip).). Fitbit health to match garmin health include fitbit premium sub for 2-3 years - then compare cost of products. If you want detailed fitness and training metrics and analytics then garmin - especially the F7 / F8 / FR265 /955/965/570/970. Venu / vivoactive are more health and lifestyle watches, and while they don't have the same level of training features, metrics and analytics than the Fenix/Forerunner/Instinct series offer - they do offer way more in this regards than fitbit does - so if that is important then would say venu/vivoactive over fitbit.
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

Ranked #1
Garmin - Forerunner 255 Series

Ranked #1
Oura - Oura Ring Series