Silk Wallet Case
CM4 (now known as Silk) makes one of my favorite wallet cases, and are finally offering one for the Galaxy S8.
It's the CM4 Q-Card Wallet case. This durable polycarbonate and TPU case will protect the entire phone no matter what. Then a leather-like material sits on back to store credit cards and cash. I don't like flip cases but I do want a wallet case. This is the best of both worlds. It's durable, strong, very usable, and doesn't add to the thickness of the device.
My favorite aspect aside from holding three cards and cash is the built-in kickstand. There's a slot in the frame where you can use a credit card or ID as a kickstand. The company made the corners stronger too, for added drop protection.