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.
Another great option, the Garmin's Vivoactive line (and some other models) isn't e-ink, it's a transflective LCD(? they call it Memory-In-Pixels (MIP)), that's always on. It's a great display that's usable in any light-level other than dark. Also a pretty good purpose-driven smart watch, especially if you want your smart watch to do things like have GPS and HR recording and integration with sports peripherals (like bike power meters, etc). Doesn't have great "apps", though. Battery life isn't two weeks, but it can easily last a week if you don't record any GPS, and a few days of normal wear + 6-8 hours of GPS recording during that period if you use it normally + exercise.
Unfortunately, the Vivoactive line seems to lag behind in tech from the product lines with the more traiditonal displays. So I've moved to the Venu line, which has an "always off" AMOLED display and better sensors. The display is also much more vibrant, but at the cost of being a lot harder to just glance at since it's usually off.
If they can bring the better sensors to a Vivoactive, I'd definitely go back to the always-on display it offers. I miss that always-on and much closer to e-ink style feel the transflective display has.
[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).