I like the look of ZJs and my friend had a '98 5.2L ZJ for awhile. It was a great Jeep but the trans and AWD transfer case seemed to be the weak points. It had a few of those annoying electrical gremlins that would come and go as well. The 5.2 is a very strong engine.
I like the XJ because it is a bit simpler, and the AW4 transmission is a bulletproof automatic. Some would say as bullet proof as the 4.0L.
The one problem that faces some 2000-2001 Cherokees is the 0331 head. This head is prone to cracking, especially if the engine is overheated. A new beefier head casting will run about $400 and is easy to replace. I did one in a weekend in the thread in my signature.