The best manual, without any doubt, is the TSM (Technical Service Manual) that you get from DaimlerChrysler for approximately $100. It will be the best $100 you ever spent. It is available both on CD (Adobe PDF format) and printed, from the Dealer. I prefer the CD which is about $10 cheaper.
Second best is the Haynes manual. I had one for my XJ which I owned for 10 years, and never needed any other book.
Least desireable is a Chilton manual.
1967 Kaiser Commando
2001 Grand Cherokee WJ
2003 Wrangler Rubicon TJ