For the longest time I've searched for a case for my Surface Pro 3 that is protective, functional, and professional looking. I've tested many and have yet to come upon a case that provides all three.
I recently tested the Leather Folio Case for the Surface Pro 3, hoping that I had finally chanced upon a contender. The good folks at GearZap supplied my review unit, but while the case offers professional appeal and is somewhat protective, it totally barfs on functionality because it muffles one of the best features of the Surface Pro 3 – the multi-position kickstand. Additionally, it provides no latching or locking mechanism for the cover, allowing it to just flap in the wind if you're not careful enough to keep it tucked under your arm.
If you can overlook the single-position kickstand of the case, it's a worthy case. You can find it on Amazon for around $50: Maroo Leather Folio Case for Surface Pro 3