I find the glass screen protectors much better than the plastic offerings.
I always used to use cheap plastic ones, they'd inevitably end up with bubbles and then awful scratches, and I'd end up just going without after a few months. Then my work phone was issued with a glass screen protector and I was amazed at how much better it was, other than there being an edge to it you wouldn't have been able to tell that it was there. I bought one for my personal phone shortly after.
I have gone through a couple of glass ones in the past year and a half I've had my current phones, but I've always replaced them and never considered going without. My current ones are chipped at the edges and cracked, but it's barely noticeable and I'd rather the protector be damaged than the screen itself. I do have a new one in the drawer of cr.p but I'm just not bothered by it enough to get round to putting it on. Cracks aren't as obvious as the scratches plastic ones pick up easily, and I've found they're a lot easier to put on without bubbling.
As for cases, I find phones these days too slim and slippery to comfortably hold without one on. The backs are still scratched, but it doesn't bother me much as it's always in a case, and at least there aren't any dents which I'm certain there would be otherwise. As the textures on the cases are different it enables me to identify my work and personal phones by feel too.
