For anyone with issues with the sensitivity of the capacitive buttons while using a screen protector, try MediaDevil screen protectors (available on Amazon for about $10 bucks)
I was using a Spigen SGP Ultra Crystal and HATED it. It messed up the capacitive buttons, where it would usually take me 5+ times to hit it correctly. And the thing was a fingerprint magnet, so much that a light touch and there would be oils all over the screen.
Switched to MediaDevil (had used them before on a few iPhones, iPads, and the Nexus 7) and everything is great. Even though the protector is completely clear, it repels fingerprints much better! It's strange to say - but this protector just "feels" higher quality (it is perhaps a bit thicker but this could be a placebo effect). And, now I have zero problems with the buttons. Don't hesitate, try these!