How are they on privacy? The issue that I have is that every wearable device expects you to allow upload of sensitive information to their servers. At this point, especially with medical information such as heart rate, I do not trust it on any computer not covered by HIPAA or under my control.
How far do you go with that? Have you examined your CPU with an electron microscope? What about the motherboard? Every peripheral? Where does it end? At some point you have to trust someone.
Apple has a good history in respecting privacy. For example, if Facebook made a watch and claimed no data is sent from your watch to their servers, I would not believe in it. When Apple claims the same, I do believe it.
Or simply encrypt everything before it leaves the watch and decrypt client-side ala ProtonMail.
I believe most people, if given a discrete choice, would sacrifice 2% of battery life and "forgot your password?" features for the privacy of such information.