Having (very briefly) owned a fitbit flex (I think -- it's the one that got recalled for giving people a rash), does anyone know of a similar device with fairly

Having (very briefly) owned a fitbit flex (I think -- it's the one that got recalled for giving people a rash), does anyone know of a similar device with fairly high time resolution, that does NOT require an account, subscription, or connection to a website/service to work? Specifically, something you can pull the data directly off the device in some usable form? OS requirement for the device connection is irrelevant, I've got the common ones (ios, osx, android, windows, linux) covered.