Need Tire Recommendation; Disappointed in Firestone H/T

I see comments and some pictures of tires getting good mileage. Looking at some of the profiles of posters I see many are running 1/2 tons. Some are bumper pulls or light 5ers.
I see many on this and other forums saying they don't get the same mileage as the 1/2 tons. I am one of those who get poor mileage and doing everything right on my 3/4 ton. I have had the BFG Commercial T/A's-2 sets. Tranforce HT's. Coopers HT3's and several others.