The parts & service for GM & Chrysler will likely be a non-issue. I have been a jeep owner for YEARS, and parts are never hard to come by. There are enough after-marktet makers that finding parts wont be a problem. As for warranty issues, Haertig may have a point; I'd do some investigating there.
My current Jeep is the first new vehicle I've ever owned,and it is about out of warranty (well, technically, it IS, as I well exceeded the mileage). I have yet to have an issue with it. But, that was something that they kept all along-simple design, easy to fix if broken (at least in the Wrangler models). Had I a choice now, I wouldnt give up my jeep, but, I would likely have gone with a more economical car as well.