I got one of these early on - it was cheap and not much else was available for the iPhone 6. It covers almost all of the screen (except the portion that curves), and I've had it on for about 8 months with no complaints - it even feels about like the iPhone's screen naked:
Power Support AFP Crystal Film Set. Don't buy the ones at the Apple Store, they're not cut correctly. The ones online come direct from Japan and are cut much better. Because of the curved screen, they don't go all the way to the edge. In fact, they don't completely cover the entire viewing area of the screen. But this is not a problem. I've had mine on for about 8 months and it is still prefect. You can find them on Amazon for $21.