Poll: are you getting a Samsung Gear S3? Which variant?
Still, both wearables are specced the same and both have the IP68 rating for water- and dust-resistance. Both take 22 mm standard straps, and both run the same plethora of apps, have S Health features on board, GPS, altimeters, barometers, and support for Samsung Pay. Of course, we do assume that the Frontier might end up costing about $50 less than the Classic and that's just about the only difference they'd have, aside from looks.
So, are you buying a Samsung Gear S3 and, if yes, which one are you going for?