The reason I choose the Otterbox protector is that it does well in anti-reflection (even better than the $40 Belkin I had last year), plus it's a glass protector so it will prevent cracking the screen from dropping.

Between 2012 to 2017, I never used a protector because when I was using my iPhone 4, I had both the normal soft clear protector and the frosted protector, and both were easy to leave scratch marks.