I've got a Fitbit Versa, doesn't do anything overly fancy (heart rate, calories, steps) but definitely found it keeps me more accountable with going to the gym and also doing cardio - I know the calories burned is way out from what I've actually burnt but knowing I want to hit X amount every session definitely makes me pick up the cardio at the end rather than just doing a lazy 15mins cool down or something
I've considered a Garmin (or maybe a Samsung) but I don't like change/do like the fitbit app, and it's sleep tracker (and i've linked it to my digital scales), so the only one I'm really considering is the Google Pixel Watch (cause Google bought Fitbit) but it's fugly as hell so not rushing to get one