I own a couple of cases - the purple Apple leather and a speck candyshell (plus have a couple of cheap colour gradient cases on their way) but I prefer caseless and that is how I run most often.
If I was going somewhere where I’d want more protection (like a theme park or something) I’ll throw a case on, but other than that I tend to go without (like all my other iPhones).
And never a screen protector. Loathe them. Nothing but a racket. I worked out how much I spent on screen protectors over a year when I had to replace tempered ones that always seem to chip on their edges or plastic ones that scratch to hell and look terrible, and peeled the thing off and never looked back. I could have bought a new phone with the money I wasted on them.
I choose AppleCare instead. And I’ve only ever needed it once - and it wasn’t me, it was my husband who broke my old phone (he gets my hand me downs).