The Fossil Hybrid[1] series with the E-ink screens is by far my favorite "smartwatch" right now, and has a ~10 days battery (claimed 2 weeks). Does basic sports, heart and sleep tracking, shows notifications, customisable watchfaces and a bunch of other stuff I don't really care about.
[1] https://www.fossil.com/en-ch/smartwatches/hybrid-smartwatche...
Edit: it shows the time using physical arrows, so you have it accessible 24/24 (they glow at night).