I thought about an Apple Watch though the only Apple products in my house are from work (i.e. I don’t use for personal things). I don’t think Apple allows you to sync with Android devices (I could be wrong here). I don’t need a super smart watch either just something to track health and fitness metrics.
Garmin products are the most open with the data they track (as far as I can tell) and the devices I am looking into have pretty good battery life as well (some of them with 10+ day battery life).
Also I don’t really like square watches (squircle?) but that is just a personal preference.
I had a Fitbit awhile ago and I really like it (before Google acquired them). I’m a little sad that Fitbit now requires a subscription to view past data (who thought that was a good idea).
It looks like the Fitbit SDK is based on JavaScript, CSS, and SVG which is something I am more familiar with than the “Monkey C”? that Garmin uses.