I've used the Zagg screen protectors mentioned in previous posts. I have one on my Galaxy Tab 10.1 and if I do end up getting a screen protector for my One, that's the one I'm going to use. There's both a full body and screen only protection - HTC One Screen Protector | invisibleSHIELD by ZAGG
. It might cost a little more, but that'll probably be the only screen protector that I'll have to put on.
For the Galaxy Tab that is a HUGE screen, but I covered it with little trouble and there's zero bubbling (after the liquid dried underneath). I was a little worried when I first put it on because I saw a couple small bubbles that I couldn't get out, but they completely went away in a day or so. Had I used a little more spray that might not have happened.