[AnotherCat]

Seems like no one is going to add much more with respect to watch or tracker recommendations. So while I cannot comment on which specific watches are best, I don't have any need for one, but from my interest in display types I can add the following focused on that aspect. Apologies for any mention by me of what you know already.

There are plenty of cheap E Ink display watches around, their complete repertoire of functions I wouldn't know except that they at least tell the time. As far as I know almost all the better multifunctional (fitness tracking, message notifications, etc.) watches and trackers use either transflective LCD or AM/OLED displays - so Fitbit, Samsung, Nokia, Sony, Apple, etc.

Nokia do make the Go which is E Ink but it has very limited functions and seems expensive for what it is; as far as I know it does not do notifications. Sony make the Talk which is also E Ink and does notifications and calls, but is limited on the health and tracking functions compared to the more capable Sonys. These are both bottom of the range devices.

The Pebble that you mention--Pebble was bought out by Fitbit (Xaomi) a little while back--used a transflective LCD display.

I think it is correct to say, there may be exceptions, that any display one sees on such devices that includes color, will be either transflective LCD or AMOLED. If the display is black and white then it may be E Ink but most likely transflective LCD or AM/OLED (as the higher end watches and trackers are).

You mention experience with phones - I have used transflective LCD sometime back on a phone (I think all the non AMOLED Nokia Symbian era phones used them) and used AM/OLED also (again a Symbian era Nokia phone). I never had a problem with them but like tablets they have very polished surface displays so if one angles the display at a very low angle of incidence to the sun one gets specular reflection. Other than that it only means having a screen with enough nits to be easily viewable in sunlight with the brightness cranked up. I assume that because transflective LCD and OLED watches attract no negative comment about daylight visibility (and azyan says theirs is fine outdoors) there is no real problem with these displays.