Have a look at this ...
I'm currently using this over my 'usual preference' of a case-mate barely there case and I must say is fits the One more snug than a bug in a rug!!
I liked it so much, i brought two in case the other gets a scratch protecting my phone !!!
Seidio Surface Case for HTC One - Black
If this has helped, hit the thanks button, it's only small but it means a lot....