I have never used a front screen protector but have always have a full protector on the back. After using the Shinomi Full body protection, back only, for one week it started yellowing at the plastic antenna borders. I peeled it off and send it back.
When I pre-ordered my phone, I had found this on eBay and ordered it just because it was so cheap and let me tell you this back is fantastic.
I also ordered others summer black some had a textured feel but I did not like any of them - just the one that I provided a link for above.
http://pages.ebay.com/link/?nav=item.view&alt=web&id=231319276473
4.7" 0.3mm Thin Transparent Crystal Clear Hard Plastic Case Cover for iPhone 6
I highly recommend this product. I've been using it for a couple of weeks now I don't see any scratching yet and the feel is very secure in my hand although the phone looks naked.