I never use cases. But then again, I break every phone eventually. My iPhone 8 has broken glass on both sides and a broken camera glass but it works well apart from that, so I was waiting for this announcement to get a new one.
Presented without comment: I always have my phone in a case and have never broken anything physical on any phone. My launch-day iPhone 8 still looks great.
On my last phone (Galaxy S8+) I was able to break both the back glass and front glass while it was in a Spigen case (two separate incidents). First time I broke the glass on any phone I've owned. I've moved up to an Otterbox now on my S20+ as I'm not going to let that happen again.