Not OP but I’ve used Garmin’s for about 15 years and over 10k running miles. I don’t like or use non-fitness related smart watch features, so I can’t speak to those or recommend a good "smart watch that also does fitness". If you want top of the line with more data than you’ll know what to do with and a ton of fitness activity tracking beyond running, the Epix2, Fenix 7, or Forerunner 965 (I have the Epix2).
A step down but still great is the Forerunner 265. The feature they all have and I think has been the most useful is the Training Readiness. It looks at a bunch of different metrics, both current (your HRV, last workout performance, sleep, stress) and chronic (your weekly and monthly total exercise amount, types of running, etc) and advises you on how hard you should train and suggests a running activity for the day. It is basically a digital running coach/personal trainer that makes sure you are getting a good mix between tempo runs, long runs, easy runs, etc. and makes sure you aren’t overtraining or if a bad day means to switch to a light workout. I normally use it loosely to inform my choices but I’ve tried using its daily training plans exclusively and it was very good at keeping me progressing.
Hopefully this helps.
