I am up to case number 4 for my Nexus 5 - I'm trying to stop before I spend more on cases than the phone is worth! My original thought was that I would not use a case at all, but I found the White Nexus 5 to be somewhat slippery to hold and I was concerned about dropping it.
Case 1 - I acquired the phone shortly after its release and at the accessory outlets near me there was almost no selection of cases specifically made for the Nexus 5. So I bought a generic/one size fits all pocket/pouch style case.
Case 2 - Google Nexus 5 Bumper Case (clear). I didn't care for the appearance and despite its claims, I did not feel it gave a lot of protection.
Case 3 - Spigen Google Nexus 5 Case Slim. Spigen seems to have a good reputation but I picked the wrong case for my needs. While it was stylish, it was a thin shell that gave minimum protection.
Case 4 - Supcase Nexus 5 Wallet style case. Meets all my requirements for protection, appearance, feel and price.
Hopefully this has been a learning experience for my next phone!
Cheers. . .