Update: I ended up buying the Garmin Instinct, choosing it at $200 over the Garmin Vivoactive 3, which was around $130. It seems all these watches have far more features than you could ever make use of; in the end I chose the rugged look and build ("Built to the U.S. Military standard 810G for thermal, shock and water resistance [rated to 100m]") of the Instinct over the more refined look and cheaper cost of the Vivoactive 3 -they both would have done all that I needed. So far so good, and I am happy with the purchase, though I find the buttons and their function not as intuitive and familiar as I'd like, so it will take a while for me to get up to speed and be able to quickly scroll through screens and options. Some GPS watches have a color or color and touchscreen display (the Instinct is 1 color, no touchscreen); I guess either would be fine, but the Instinct is a huge upgrade over the 10+year old Forerunner 305 I was using (I don't mind the non-color display), and I didn't want to fuss with a touchscreen (a running friend has said heavy raindrops can activate his touchscreen).
I've yet to try any of the navigation features (but am happy to have some of these tools I will likely make use of down the road)- most of the time I'm running or riding on familiar paths. I ride 2 or 3 bikes and run, so wanted a wrist not bar mounted unit; my bikes already have cycling computers so I can quickly tell pace and distance without looking at my wrist.
My old FR305 was so big and clunky and with such limited display that it didn't really function as a watch, only as a GPS unit - something I'd take off immediately after my activity. I like that I can wear the Instinct as my regular watch, not needing to pack/ remember to pack it separately in my bag before preparing to head out. (Though this won't factor in whatever you may choose if you're shopping - everything these days works as a regular watch).