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

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S70 - 42mm because I love golf...but have been doing a lot more riding, running, swimming, strength training and other stuff.
In the same boat here. Exact same switch and exact same sentiment.
Got an S50 coming from a Galaxy watch 3. Will never go back. It's lighter, battery is 10 days compared to 1, and does everything I actually used the Galaxy for except make/receive calls and honestly that was more a novelty than a useful feature.
If you look at the new S44 or S50, they are great watches, but require a subscription to get both the green map and the high resolution hole maps. It’s 10 bucks a month or $99 a year. I bought an annual subscription when I bought it… But I’m seriously questioning renewing it. I don’t like the idea of paying the entire cost of the watch in 3 years of sub fees. I’m seriously considering switching to an Apple Watch and using The Grint app. I would rather pay that subscription fee for the stat and handicap features. I’m also looking at shot scope watches for the single reason they are subscription free.
Yes, I can recommend the Garmin S50. I've been a regular watch user for 50+ years, but all I wear now is the S50. It looks great, it has all the same smartwatch features you like, and it's light on my wrist (not as big as the S70).
It depends on how important regular smart feautres are contra the golf watch aspect. If your dad is like me and the only real smart features he uses is notifications, then go with a Golf watch. If he uses many other smart features on the daily, it might be worth getting a regular smart watch. However, if golf is the most important, then a Garmin watch will absolutly destory a normal smart watch in golf related features. The higher options such as the S70, Fenix and Marq series are excellent fitness watches in general. Any of the new Garmin (S44, S50 and S70) are good golf watches, but with different features unlocked as standard. I personally have an S44 as I don't use other fitness features and "Plays as" and similar features are not allowed in competitions anyway. But if he wants the full monty best Golf smart watch, with a few extra bells and whistles, then get the S70. Bit more expensive, but you get a lot of features with it.
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