My XJ is awesome in the snow; 4wd, rear disc brakes, and four studded snow tires. Probably the worst thing about the XJ IMHO is that the factory rear brakes are WORTHLESS, so when braking on slippery surfaces in 2wd with an auto trans the rear wheels will push the front end around. A Teraflex rear disc conversion eliminated that problem in my case, after sliding through an intersection with my family on-board I wouldn't tolerate the stock brakes any more. ZJ brakes can also be easily adapted, but for $400 with all new hardware I thought that the Teraflex kit was a good value.
I think the sweet spot for newer XJ's is '97-'99. The '00-'01 (which I have) introduced some new issues. Get a 242 t-case if you can find one (very rare), the full-time mode is awesome in non-dry conditions.