I bought the XR late October. Since then it was in a case for the vast majority of the time.
However, I didn't like the cases so now the phone is caseless and skinless. It's been like this for about a month now and everything is fine. I have a small scuff underneath the right antenna band (above the power button), but this happened a few months ago while I was using the case, ironically. I have no other scuffs or any marks on the phone other than that.
I pay attention to this beause I decided to not have anything protecting the phone so I keep track of whether something appears on the frame or the glass. So far so good. My wife has scratches on her Galaxy phone (glass has no screen protector anymore), she inspected the XR's display and couldn't see a single scratch.
So if you want to go caseless with the XR, apparently you can, but maybe someone else will share a different opinion. I found that using the phone without a case or a screen protector is a much better experience. Decided to go caseless as I almost never drop the phone so here's hoping the "almost" part happens on a not-so-hard surface.
I never used an Apple Watch so don't know about the comparison.