We had a 1996 Grand Cherokee (ZJ) and it was a great SUV. There were a couple things to keep in mind:
1) We had the smaller V8 - was OK, but required all-time 4WD (Quadratrac)
2) Interior isn't that big - comfortable, but not a lot of storage
3) Rear axle was a Dana44, but light duty (aluminum housing IIRC)
4) We had very few problems with it, but replaced the AC system 2x
5) Stock tank was 21gal, IIRC - we had a range of about 350 miles
My Brother in law has a 1986 FSJ (Wagoneer) and it's a beast. It has the V-8 and gets about 8mpg.
He swapped in Dana 60 front and rear with atlasII xfer case and ARB air lockers front and rear.
The vehicle has had a roll cage and bunch of armor added to it and the weight is somewhere around 8000#
Very capable truck, but frankly it's got too checkered of a history for me to trust in the back country - maybe different if it was from Wagonmaster or something, but I want something more reliable.