I would recommend the XJ, just simply because of the years of quality refinement. The ZJ and WJ are considerably more complex vehicles, which means there is more to go wrong. The additional weight also reduces payload and economy.
Just my thoughts.
My 1996 ZJ did not prove very reliable, with a trans change at 54,000 miles. My 93 however, was rock solid up to 100,000 miles, then some little electronics issues.