From my experience with several XJ’s and a few MJ’s and ZJ’s with 4.0’s, l would say the 96 4.0 HO was the peppiest of the bunch. I had 89,92,95,96,97, 98,99 and 2000 XJ’s.
89 and 92 MJ’s
Had all those years with 4.0/AW4 automatics in the XJ’s.
The Mopar tranny in the ZJ was junk compared to the AW4. Otherwise I liked the 3 ZJ’s I had. Not as much as l liked my 98 XJ with the 4.0/AX15 and 4.10 gears on 31’s and 32’s. Ended up with 453k on it when I junked it. The engine was never opened up.