Are you looking for a road tire for strictly towing, or something all-weather that will also be good in snow/mud?
For a street tire, I'd go with the Michelin LTX M/S2. No personal experience, but I've done a lot of research and these are always at the top of the reviews.
For my personal trucks, I do some mild offroading and deep snow, so I get something more aggressive. Have Bridgestone Dueler A/T Revos on my half-ton. On my second set; the first set lasted ~50K miles, with ~15K of that being towing. Very pleased with the performance and poor-weather traction.
On my 3/4 ton, I have Goodyear Duratrac tires. They're marketed towards commercial snowplow customers. Very aggressive and blocky, but not noisy. Outstanding traction in mud, snow and ice. Dragged the TT down to AL over the Christmas holidays, 2000 mile round trip, and the tires did great. Downside - no treadwear warranty offered, but the reviews I've read give me reason to expect them to last 40-50K.