I used a Spigen Glas.tR first, but it broke. Then I bought a Nilikin, but after only a week I've already ordered a Glas.tR to replace it. It costs three times more, but is worth it.
First of all, the Nilikin has scratches already, while it took months for the Spigen to get to that point. Secondly, the glass holds fingerprints more than Spigen, and I don't like the feel of it.
BUT, the Nilikin actually has a better package of tools to mount the glass. Instead of a useless plastic protector for the front of the glass, it has a little "dust remover" which is simply a sticker you use over and over again until you've used it on the entire screen, making it easier to be sure it's clean. Of course, a simple piece of sellotape does the same thing.