Very very picky about cases. I agree with others above that the N5 is far too beautiful to cover up. For me, that extends to having a tempered glass protector that you can see 5 feet away. This also detracts from the beautiful design as well.
All that said, I need some amount of protection. I own about 5-6 cases and until recently the Ringke Ultra Slim was my choice. The Ringke is an absolutely minimalist cover for the back and sides, providing a nice slightly rubbery surface to ensure no-slip handling. All of my other cases make the N5 look and feel humongous.
Recently, I got a Samsung promotion and was really challenged finding things on their site (it was "Samsung Money") that I really needed. So, with about $30 left completely unspent, I threw it at a Samsung case that I once read a review on, saying that it' was amazingly minimalistic, but expensive. With nothing else to spend the funds on, I bought it. It's beautiful.
The Samsung "case" is really just a phone "back" and "corner bumpers". That's it. The sides are totally exposed, the back is the exact color and look of my Black Sapphire N5, it's contoured perfectly, and there is a bit of protection on the corners. Due to the slight edge it provides on the sides, it's much easier to hold than a naked N5. IMO, this case is so good, and unique, I'd throw down my own cash for it. This is exclusively for picky N5 owners, definitely not for the Otterbox "my phone needs to survive the apocalypse" crowd.
More more thing: I exclusively use a film protector on the screen. I still have a number of glass protectors left over from experimentation, but I just can't get past the look of the N5 appearing like Mom's favorite table in the living room with the 100 pound 1/2" plate of glass on the top. Film protects enough, feels good with my finger and S-Pen, and is virtually invisible, even up close. For me, that works.
Hope this helps!