Tj is way easier to work on mostly cuz there's way more room around the engine, and no unibody problems to deal with. also way less "stuff" like power windows, mirrors and trim parts. I would imagine the TJ has to have one of the lowest parts counts of any car built since the 70's Cherokees are pretty much disposable when used hard on the trail unless you beef it up a lot before you start since the unibodies flex madly and will develop cracks in several areas. Cherokees are way more stable at speed, have less bounce and body roll and can climb steep short slopes way better than a TJ. I have taken my XJ up a basically sheer ledge nearly 10 feet high...as long as the fronts come over the top before the backs get to the sheer face, you can just power up it. Trying the exact same obstacle in my TJ, it either wouldn't make it or would tip over backwards. TJs are way better at flexing over off camber twisted up sections, It is amazing to feel...the xj will usually do the same trail but with much more body movement and some horrid creaks cracks and pops from the unibody. The Xjs have way more bang for the buck though, You can pick up a nice one used for less than $3000 and sometimes less. I got mine for $100 with minor front end damage. XJs are also cheaper to lift with the rear leafs...if you get creative and don't mind a few re-purposed junkyard parts.
XJ, TJ, I love 'em both....do yourself a favor and get a 94 or later XJ though...