Thar Petrol RWD AT. Vs Diesel 4WD AT.

Planning to get a Thar for coastal roads in Karnataka, I stay in udupi, really confused between RWD At. Petrol or Diesel 4WD AT. I need an automatic transmission, my family has cars already, this won’t be my only car, this is basically just for trips in and around Karnataka. Plan to keep it for 5years. Roughly 900-1000kms a month. Don’t need a 4WD vs RWD comparison or “Thar is only supposed to be 4WD”😭, yes I am truly aware of that, looking for genuine petrol vs diesel transmission comparisons considering the 3L difference.