Get one that works best with your other digital portable devices such as a smart phone and a tablet. So, Apple for Apple, Android for Android

I have had three generations of the Samsung Gear and the subsequent Galaxy watches. Am wearing the Galaxy 4 currently for daily use, and have a Galaxy 6 in reserve because I like the featured rotating bezel on each of their faces. Rotate the bezel to get to apps and information/data.

I have no experience with Garmin or with Apple, so I can't in good conscience comment about them at all.