A little late to the party, but it’s never too late.
Over the years I’ve used the Suunto Core Black (simple ABC watch, no tracking), Suunto Ambit 3, Suunto 9 Baro, and am now using the Garmin Fenix 6X. For context, I use it for track workouts, skimo, ski alpinism, mountaineering, but mainly trail and sky running.
Overall: the Fenix 6 is a superb thing. Now that Garmin released the 7, you might get a good deal on the 6. Suunto 9 is an option too if you get a good price for it.
Both Suunto 9 and Fenix 6 have very long battery lives, decent sports modes, configurable screens, don’t look too vulgar, can be used with frozen fingers in big gloves, and have accurate GPS tracking.
What Fenix 6 does better than Suunto 9:
– workout mode: sync TrainingPeaks to the watch, zones, times, etc all there
– the HR strap is reliable. I’ve had serious issues with the Suunto 9
– while in workout mode, you can use any other aspect of the watch, like stop watch, timers, etc
– it displays an actual map
– the music player is surprisingly handy
– the software on the watch is just better in lots of little ways
What Fenix 6 does worse than Suunto 9:
– there’s no way to display lap average vm/h (I used that a lot)
– the app is awful to use
– the Fenix’ clever sport modes (climb pro, etc) are too buggy and clever. I don’t like clever when I’m tired.
– the Garmin app has a lot more outages than Suunto’s
Regarding size and variant: I chose the large version (58mm?) to see more at a glance and sapphire glass as I bash it around at all times. You might want something else.