I loved my Pebble Time (Steel) and currently own an Amazfit Bip. Both of these get right that a smartwatch should be a watch first, meaning being low-maintenance and reliably telling the time. The Pebble lasts 10 days and the Amazfit Bip about a month, both can do it because because they have E-Paper (sharpy memory LCD) displays.

Pebble in particular got it right: No touch screen. The Bip's touch screen is fine when compared with others (works when wet), but having to use it is still a gigantic pain (touch screns on smart watches, what an insane idea). My benchmark for usability is "can I skip a song on my phone while looking somewhere else".

That's of course in addition to nice build quality (aesthetics are important).

Something I would also like to see is good haptic notifications. Both the Pebble and the Bip make your wrist numb through long vibrations, while the Apple Watch (apparently) can simulate a light tap and even give you directions that way.