I have always used screen protectors going back to the original iPhone. Usually, if I get it installed correctly, I can leave it on without replacement for a long time - sometimes even the life of the phone. I've had some get fairly scratched up, but my screen has never been damaged - it's always been pristine - so I'm glad the protector took the scratches instead.
I might be an oddity here, but I don't mind a good quality PET plastic protector and I feel like glass is somewhat a fad. My previous PowerSupport and SGP plastic protectors lasted a long time, without peeling or getting too scratched up. I jumped on the glass bandwagon last year, and tried a Mime feather tempered protector with a good following. I had to change my case from a Tech21 case I loved to a much less protective Spigen case so the sides wouldn't peel up. While it felt marginally better to the touch, and may have been easier to clean oil off of, it cracked on the edge within five months. The phone was not dropped. I had a hard time removing it, cutting myself in the process, and even though it was tempered, the screen was scratched a bit at the crack site from the broken glass. I would be very reluctant to go with glass again, because I feel like they are less likely to work with cases due to thickness, likely to crack and have a much higher chance of scratching the screen in the process. I honestly don't mind the tactile feel of the SGP Crystal I have on my phone now. It looks good, hasn't scratched in the 9 months I've had it on, doesn't peel, and I can use a much greater variety of cases with it. I also am not a fan of the wet install screen protectors that use their own adhesive. These are a pain to install, remove, and I always worry the adhesive is going to rip away the coating of the actual screen.
My observations are based on iPhone 5 series and older, and I know the 6 Series is a different beast entirely due to the curved screen. It's my understanding that many, if not most, screen protectors, plastic or glass, have either peeling problems due to the curve or are cut way too small in order to avoid it. It's a shame.
I'm looking to upgrade to a 6S, and am looking for a good protector. It seems like PowerSupport has all but vanished from the US market, and the Spigen SGP Crystals are cut so small they don't even cover the display area of the screen completely. I'm not especially keen on having the screen protector not be edge to edge on the 6 like it is on my 5' - with the sides of the screen open to scratches, dirt/oil collecting along the lip, and having my fingers run over the seam edge when using the phone - but I certainly don't want the edge to be over the viewable area of the screen (like pictures show the SGP on Amazon reviews). I also don't like that Spigen is paying customers to give it good reviews on Amazon.
So, does anyone have any recommendations or first hand experience with a good screen protector for the 6S? Preferably plastic PET static cling. I see a lot of posts on here for glass, but hardly anything for plastic that's relatively current. I will probably go with either the Apple leather or a Tech 21 case. Thanks!