There is no such thing as "The most profitable truck". It all depends what you are using it for. You get a truck, the same as you get a rifle, for what you want to do with it. If you want to hunt Squirrels you don't get a 458 Mag Weatherby or 500 Nitro Express (well some might
) the same with trucks. If you are going to pull light vans regionaly you don't need a 600 Cat or Cummins with an 18 speed but if you are going to haul 150,000 lbs coast to coast with a 300 FL and a 10 speed you may need a little more
Look at what you want to do on a regular basis then find the happy median. My truck gets 2 to 2.5 mpg on a regular basis and is real profitable so I am real happy with it.