I was actually looking at the Suunto (I already own a Suunto dive watch), but don’t really like the Movescount software. Plus the Garmin has better Strava integration (from what I’ve read).

As for Garmin, the Forerunner 935 is internally exactly the same, but as I’d like to use it as a regular watch too, I preferred the looks of the Fenix.

EDIT: to add to that, it was recommended by a friend that owns a Fenix 3.