Silk Base Grip Case ($12)
Silk is one of the top case brands for the iPhone, and they now offer a few options for the Galaxy S8+. The model that looks the best is the Silk Base Grip case.
The company uses a patent-pending texture on the sides of the phone for improved grip. This will keep you from accidentally dropping your phone. See the Amazon listing for more pictures and a better idea of what to expect. It's similar to that texture on a handgun grip, and I love it. Additionally, it has a soft TPU design for added drop protection. The TPU material curves over the sides of the screen so it doesn't contact surfaces when laying face down. Silk makes great cases as you can see from all the Amazon reviews.