IMO
97-99 Best Models- Full door windows less bugs. Fuel filter in tank with pump. I like to change often kind of a hassle
95-96 arguably just as good. 95 did not have OBDII
91-94 HO engine strong just gonna be older in general Vacuum everything is my negative
88-90 Renix Same as 91-94 just less horse Power. Some say not as strong but that is a huge debate. Vacuum everything is my negative
2000-2001- Heads Crack I would avoid these. nothing against them just very suspect.

I have owned a
89 5spd that had 279k on the clock original drive train when I traded for a truck. Mom bought new and I got when I was 14. Ran like new. Has some blow by but not a ton.
I own a
95 auto that has 296k on the clock. All original Drive train. Has had new head gasket. No blow by runs like new. Small leak on Oil filter value o-ring.

buddy has an 88
245K on clock rear end issues due to 33s on dana 35 I think other than that runs like new.

another buddy has
98 180K on clock
All kinds of issues with his. He hasn't had it very long though.

Common Problems/issues with all are Fuel Mileage they just are not that great for today's economy. Depending on location Rust can be an issue. Motor Mount Brackets can break off of the block due to thread boss's being to shallow. Death Wobble can drive a person insane. usually an easy fix just hard to diagnose. Over Heating. same as death wobble easy to fix hard to diagnose. Neutral safety switches get dirty and go bad. Taking out backup lights and wont start without playing with shifter in park or neutral. Blow by usually high mileage. Not a major issue as long as you keep the oil checked and filter clean They can run for ever like that. Hinge mounts can be suspect to breaking off on some. That probably seems like alot and I am missing a few things I'm sure. Not all of these things will happen to all jeeps. Even if I had every single issue that was common. I would still own an xj.

Cherokee's can run into money but its is mainly because of upgrades. Parts for these are everywhere at JY big plus compared to other Make's.

 

Definitely look into a 98-99.5 for the best intakes and heads.
I think the head cracking issue is a tad over dramatized, as I have a 2000 XJ with the 0331 head and it has 217,000 miles and still runs like its brand new. Shows you just how maintenece and care will pay off in the lifetime of these vehicles. Look for one with a 4.0 and find the least amount of miles you can. Look for a Chrysler 8.25 rear axle if you plan to wheel/upgrade it. Sports are the most common trim level, SE are the very basics and Classic and Limited are high trim levels with the most options. 2 doors are a lot rarer and thus tend to sell for a lot more. 4 doors are more practical IMO, there are no wheelbase/length differences. 2000-01 models went to a Coil Pack ignition system. Check for rust! Its commonly overlooked and one of the most regretted. Check for oil leaks, rear main seal in particular. 4.0s are imfamous oil leakers. Check the engine bay and components in general to see if the previous owner took care of it, I've seen some stories of people finding no coolant in the bottle and other stories. Just be sure its right for you before you sign that check