Personally, if I am totally honest, the very first screen protectors I bought for my iPhone 6 were these ones:
http://www.spigen.co.uk/iphone-6-screen-protector-crystal-4-7.html#.VEeDRxY091A
Obviously, they are not glass tempered ones but I think, these are just as good. They leave a very slight gap all around the iPhone 6's lcd screen (about 1mm - just like the tempered glass ones do), however, these ones are super silky smooth, they show NO fingerprints, there is no 'rainbow' effect like cheaper films show and are obviously a lot thinner than glass shields, and finally - they come in a pack of 3. I've had mine on since release day of the iPhone 6 and can see NO scratches (not even hair line) on these at all.
I've looked around at ALL other glass tempered shields and the reality is, I am not happy with how ANY of them look on the iPhone 6.
Don't really go for the 'wet install' variety either as these all tend to have that 'sticky rubbery feel' and 'orange peel' look - both which I hate!
In my view, you can't beat Spigen's Crystal Clear protectors (and NO I don't work for Spigen!!)!
I had these for the 5 series, loved them at first but when that oleophobic coating wears off, man oh man... They started producing hairline scratches and got worst over time.