The most privacy respecting watch in my opinion is the viita watch. Still not open source but you can use it without a cloud service.
Quite more expensive but more sport options :
If i am not mistaken this watch uses the same software - also not open source but cloud free.
I own a viita watch which works as expected according the description on their webpage. The only downside is the fact that it is cloused source and impossible to sync it with an own server application. You have to stick to their android or iphone app.