Another vote for the crystal film cover from Power Support. It's hardly noticeable.
PSAG film for sure. It reduces glare, and eliminates fingerprints while adding a matte feel/texture. I love not having to clean my screen every time I use my phone. If you put it on right, you can hardly tell it is there. Plus, it does use glue but rather static cling so there is no residue if you decide to take it off.