Personally, i never use phone covers/screen protectors. I relate it to encasing your brand new car with plastic covering in the seats. Sure your seats will look new a bit longer but it totally ruins the seating experience.
When companies spend millions of dollers on R&D and Production cost to come up with fancy polycarbonate plastc, Glass, Aluminium alloy etc etc..whats the point of covering it up with a ugly case. My finger is pointing at those guys with HTC One. You spend so much extra for the looks while completely covering it up and making it ugly. My other finger points at the girls who use iPhones 5s with pink floral gay as hell plastic encasing. Why dont they just buy the cheaper 5 c instead ? Its not like they are gonna need that 64bit computation power(or finger scanner)
As for the screen protectors, the good ones are quiet expensive (minimum Rs350) and they need to be replaced every month since it wears out a lot. The cheap Rs100 ones are a NO NO... Moreover, all these screen protectors hamper the viewing experience. And like i stated before, why downplay the utility of awesome picture fidelity of those awesome 1080p IPS displays with screen protectors.
The phone i have used the longest is the Samsung Galaxy Ace.(3yrs) banged it, tossed it around, had battery changed twice due to bloating and swelling..still the screen looks good, the body is top notch except for the cheap chrome sides which have worn off. In fact the matte-grey layer that got exposed looks better than the chrome plating it had before.
Phone casings are overrated.
The only casing i will ever use is those transparent glass like casings. At least it will show of the expensive body work of the phone. But then the good ones are expensive and STILL they are 10 times more fragile than the phone itself.
As for Gorilla Glass, they are way more durable than you think. Like i gave my Galaxy Ace experience.. NO scratch after 3 years of torture. Its the screen protectors that scratch easily making you enter an infinite paranoid induced loop of buying over and over and over and over again....