NOTE: I now have my little daughter around so you might hear random outbursts.
I only have two cases for the HTC One Max currently. Both are very popular. There's the Otterbox Commuter case as seen in this video and the Incipio DualPro. I purchased it from a retail Verizon Wireless store.
The Commuter is a little bit wider, taller, and thicker than the DualPro. It feels really tough, and I'm sure would protect this device for the highly active user. The port covers will deter most dust, debris, liquid form going directly in them.
I have to note that out of all of the Commuter cases I've owned, this is the hardest one to fit on the device. The rubber barely wants to align with the plastic. It's not a deal breaker. Most people would probably be turned off by the size more than anything else. The plastic does allow the case to slide in and out of pockets a little bit easier than if it was all rubber. Only draw back would be grip while holding the case, however it isn't that slippery if your hands are dry.
Available in black or glacier currently. Just like the Defender series case. Retail cost is $44.95.
At the time of the video, I couldn't find these on Otterbox's site. That's changed: