I think for your application, get the 3.0 Duramax and don’t look back.
quick math, using these assumptions:
25k/year at 65% Highway/35% city.
So, 16,250 Hwy and 8,750 city miles.
Diesel, assume 28MPG Hwy, 20 City
Gas, Assume 19 MPG Hwy, 14 City
Diesel = 580 gal Hwy, 437 gal City = 1017 Gal...