I am most certainly an Apple fanboy, but not for the wearables. I have been using a Garmin Fenix as my daily wearer for 3 years now. First, with the Fenix 5 and now I wear the Fenix 6x.
It supplies a ton of data. If you're a runner, the metrics it measures (especially coupled with a Garmin HR monitor or the running pod) is pretty amazing. It also keeps track of a ton of other stuff that has turned out to be helpful. For instance, I could tell I had Covid, even before a positive test, by my "body battery" being low for consecutive days despite sleeping normal duration.
Battery life = weeks.
Anyway, it's amazing and I'll never wear another brand's fitness/smartwatch ever again. They're expensive, but worth it to me. Here's a review: