I dig both black options.
For jet black - Clear protective layer on the back. Not just to protect it from fingerprints or scratches, but creates traction with slippage.
For matte black - No need for one although it will still attract fingerprints and blemishes but not as often. It also doesn't have the slick, seamless surface as the jet black to apply a clear skin on the back.
Both are nice. Far and away the best-looking from the iPhone 6-like design. Just find a decent solution for the jet black rear because it should feel like a bar of soap while the matte black will hold up better completely unprotected of anything.