I used Anker film protectors on my 6 Plus and 6s Plus with no issues at all. In fact, having had zero success recently with edge-to-edge tempered glass protectors on my 6s Plus, I've reverted back to the Anker film ones.
I like both glass and plastic amFilm screen protectors. The plastic ones come in a three pack while the glass ones come in a 2 pack with plastic tabs to aid in installation (similar to Spigen). I never liked plastic screen protectors, but I was pleasantly surprised with these when I temporarily put one on. I was most surprised with the fact that you could hardly see it on there. There is a difference in overall feel which is why I prefer glass over plastic.