For something with fitness tracking, I’ve been using the Garmin Forerunner series for years. Recently though, I’ve been using the Pine64 PineTime as my main smartwatch. It doesn’t have much for fitness tracking, but if you’re looking for a basic smartwatch it’s pretty nice!
My only major complaint is their free-tier is a bit lacking compared to what Skiff had (or I guess has, but not for much longer.) I think their platform is great, and definitely worth paying for, but given I’m a broke college student that’s not much of an option. Also their support for third party clients (or lack thereof) isn’t great, though I don’t use those as much. Otherwise I like it quite a bit!