The 5.3L will give you that low end torque. Love the torque in my Avalanche. Even better would be the Sierra duramax.The fuel economy is pretty much identical to the GMC Sierra 1500 4WD that I'm looking at, lol.
Can't vouch for the fuel economy, tho.
FWIW, my wife's '15 TSI Passat gets about 28 MPG overall and is quite torquey (?) feeling with the seven-speed transmission.