Hercules Terra Cross, they're solid, good on the road too
The top rated 33X12.5R15 mud tire at the tire rack is the Firestone Destination M/T. In that size it goes for $176 a tire, which is $704 plus shipping. If that's out of your price range, try the Kumhos. Their Road Venture MT KL71 in that size is $668 for four plus shipping. I've had good experience with Kumhos, so don't dismiss them because they are Korean. The Dunlop Radial Mud Rovers are only $140 each ($560 for four) but they are only rated good on ice, if that's important to you. My experience with the Tire Rack is that they are knowledgeable, quick, and fair priced until you have to pay for shipping and installation. My local independent tire shop always beats or meets their price, shipped and installed. Part of that is because most tire stores will charge you extra to install and balance a tire you buy elsewhere. Part of it is because my shop knows me and knows I will recommend them to all my clients and friends.