One of each is a good mix

My gf has a grand, i've got a kj, my good friend from the Corps has a TJ
The KJ makes an Excellent accessory to the TJ for camping trips
I would have alot of trouble packing what I tend to take (which really isn't much) in my friends TJ if it were mine
I have no problems what so ever packing anything and everything I need and living/operating comfortably out of it for week(s) at a time without going back to a store for resupply
The grand space wise.. eh.. there's simply alot of space there that I'd not use, the TJ.. simply not enough space.. i'd have to yank the back seats out and sell them if it were mine
The KJ fits my needs just fine, it has it's Con's just like anything else, but none of the con's have even came close to making me regret choosing it as my DD and offroad build
The only thing that I really do wish was different was that it had the grands V8 or a decent diesel
the 3.7 once armored and lifted gets about the same mpg as the 4.0
I'd certainly say that the 4.0 is a more resilient engine to things like an overheat or an oil pressure loss, where the 3.7 will set your wallet on fire if one of those occurs
but.. the XJ's can be very nice vehicles
I'd say go with the XJ if you have any question that the IFS on the KJ will keep you from doing what you want
You should be able to get a well taken care of low mileage KJ for around 7500, not much more than a low mileage XJ
If you want a stock TJ i know where there's a REAL nice one that's been taken care of and never been offroad for 7k lol