After looking at all of the wallet cases available on Amazon, none of them really looked like they'd be very practical to use. I really wanted a flip style case though, so I went ahead and ordered this one: http://www.amazon.com/Poetic-FlipBook-Black-Manufacturer-Warranty/dp/B00BKOWJCC/ref=sr_1_1?ie=UTF8&qid=1367737516&sr=8-1&keywords=poetic+htc+one Still have to carry a wallet but I like the screen protection that flip style cases provide. It hasn't arrived yet, but it has 4.5 stars on Amazon.
Poetic flipbook is the case I decided to purchase. It lays perfectly flat against the phone almost as if there is a magnet. There's no "break in period" or anything as the HTC branded flip case. I've dropped it twice and it took no damage.
http://www.amazon.com/Poetic-FlipBook-Black-Manufacturer-Warranty/dp/B00BKOWJCC
I have the Poetic Flip Case that has mentioned by everyone else. My only complaint is that the cool Poetic logo starts to wear. Mine now just says "Poe".