the 4.0 for sure. Yes it doesn't have all the punch of the v-8's, but it's built to last, parts are cheaper. The v-8's are more complicated to work on as well. I don't know how skilled you are in fixing things but easier is easier lol. That just my two cents.
Just bough a 2000 with the V-8. I had to it was in too good of shape.