I have tried several, current one is a Carbonix - it has been the best by far but still not accurate in steps counted. Still about 25% off if I count out 100 stepps it will say 75 (others were 50-75% off)  And calories burned, working 8 hours of construction, I burn 287-340 calories LOL

The Health stuff is pretty accurate it take blood pressure every 10 minutes - comparing it's reading with an actual cuff generally within 3 points on the top, and 2 on the bottom. Heart rate is also accurate, as well as oxy level.  Stress level and mood are kinda useless IMO

It also has a sleep tracker, which surprisingly has helped my sleep patterns - who knows maybe just being aware helps with subtle changes