Yeah, I think the only difference is the inherent risk of damage when offroading which pushes a little bit more towards the cheap option.
While you can take your bone-stock (well, with oil cooler) Z out for a track day, keep it at 8/10s, and then drive home with fairly low risk, the same cannot be said for a real wheeling trail. I figure you are generally dropping $5K just to get the underbody protection you need, nevermind all the other nice-to-haves.
Cheap tends to get people into a much more capable car, because an XJ with five grand in it will spank a bone stock TJ, and probably cost less.
When you get to anything really extreme, your base platform is pretty much just providing a frame, and there's a different set of concerns. Once you get to that point, it's probably best to get advice someplace other than a Z forum.
Bummer to hear about your XJ. I miss all my jeeps....posting in this thread has me browsing Craigslist for replacements
One thing to keep in mind if you are the prepper-type is the limited storage inside the Wrangler, unless you get an Unlimited. You also might consider a hardtop if you go that path.
For your goal, you don't need much in the way of capability. I would spend your mod funds on underbody protection (especially oil pan), perhaps a small lift, and some knobby tires. Once you get a little more proficient, you'd probably look at lockers and some other items, but really armor should be all you need to get going.
My platform suggestions would be LJ or XJ, but I think you could get away with most cars, provided you were willing to take on the risk, as well as spend the money protecting the critical components.