The first iPhone case I purchased was the iPhone 6. The back of the iPhone 6 and 7 is too slippery. I have dropped and broken my iPhone 6 and was concerned about dropping my iPhone 7. I use the Apple Saddle Brown case.
I never used a case on my previous iPhones. I prefer my iPhone 4 and iPhone 5 "naked". I never dropped either of those.
Typically I use a case, my last iPhone purchase was a 6s Plus and I found that I really didn't like using a case on it. I own a few, but I prefer it naked just like you. I've never broken a phone, but I know sometimes I drop it and the case makes me feel better. I said all that to say, about half the time my phone is naked lol, right now it just happens to be in a white Apple case of iPhone 6/6s Plus.