The lack of HealthKit integration and needing to use half-assed hacks like the sync apps on the iOS AppStore really turned me off fitbit. Since their API doesn't let you pull anything but basic data like steps walked you were effectively locked into their little garden with your data.

I'm much happier with my Apple Watch as a fitness tracker, I wish the battery was better and it had sleep tracking support because that's the one feature I seriously miss from my Charge HR.