Otterbox Defender. Cases are a must with a smartphone with dual Gorrilla Glass 4. GG4 is more scratch and impact resistant but is not immune from being shattered.
Cases are for protection not aesthetics. If you want to show off the GS6, go commando, IMO. Other cases are fine but for klutzes like me a rugged case is in order. I am pretty confident of an eight foot drop onto concrete. With past Defender cases, I have had a smartphone survive a drop down a flight of concrete stairs. With all my cases, especially the GS3 and GS4, people were amazed at the pristine condition of my devices. The Defender for my GS6 is much more compact and slimmer, probably the slimmest to date of any Defender that I have owned since 2006. The grip is great and it feels rock solid. It is easy to assemble. Check out my YouTube channel for a review of the case. Whether you get metal, silicone, rubber, TPU aka plastic, consider whether it would survive a fall on to concrete. Choose what works best for you. Insurance claim or full replacement cost are far greater than the cost of a good case. Otterbox doesn't make the only rugged case. There are tons of other ones. Ballistic, Seidio, Spigen. Lifeproof. Just don't deliberately slam it on to concrete.