I agree R2.8 is tops of my list as well. A lot of the diesel swapped jeeps are TDI's and i prefer to keep my distance to VW engines, so all diesels are not created equal.
My driving style on road and off, I'm all about that torque down low. I saw
@toximus hitting in the 4K's RPMs i NEVER drive like that. I rarely go above 3K RPM so the R2.8 with 270 ft-lbs at 1800RPM without a tune sounds absolutely perfect for jeeping. Really for me, engine swap talk is all about on-road driveability. I have zero issues with the 4.0 at my local ORV parks.