When I got my 6 Plus, I tried quite a few glass screen protectors, and I was only happy with one brand which wasn't the cheapest, but wasn't the most expensive either - JETech. The prices have dropped even more now I've come to buy for my 6s Plus, £5.45 for 1 or £5.95 for two from Amazon. Other brands I had bubbles or edges didn't stick properly....
I always keep a spare, they don't have unsightly bubbles and are much, much easier to apply than the non-glass protectors. Saved my 6 Plus screen multiple times - from when I've dropped it, knocked it off a kitchen worktop corner, or had it knocked out of my hands... The protector cracks but the screen is absolutely fine.
Link:
-Premium-Tempered/dp/B00U5M5XMS/ref=sr_1_1?ie=UTF8&qid=1445776541&sr=8-1&tag=macr0e-21" target="_blank" class="link link--external" rel="nofollow ugc noopener">http://www.amazon.co.uk/iPhone-Prot...5XMS/ref=sr_1_1?ie=UTF8&qid=1445776541&sr=8-1