With a phone this large and a price tag to match, I want a case. Not only for the protection but also for the ability to hold onto it better. Currently using a clear Otterbox Symmetry case. I like the rubbery feel to the edges. Not so much the back as it is a smudge magnet. Have a couple of others coming to see which wins out for daily use. I do like to rotate though so nice to have options. I will be adding an Apple leather at some point.
My favorite type of case was back in the 4s days. The bumper only cases were the best. Gave the phone protection but also allowed you to feel the beauty of the phone. I believe Rhino Shield makes them. If I were ever to consider going naked, I'd at least go that route again. That or at the very least I'd put it in some sort of sleeve when not actually using it. Joli makes wonderful leather & felt lined sleeves.