The tcase is very vulnerable, without some sort of added protection. Personally, I run a tcase bucket on my samurais I take offroad (it protects the bottom of the tcase, doesn't have a large area that hangs low, to catch/snag on stuff and it ties the arms together, so it adds quite a bit of strength, IMO).
One of the guys I wheel with regularly runs a full skid. So far, I have not been impressed. There is a lot of area under there to hit on rocks, ledges, etc. It also hangs down below the frame (because the tcase hangs down below the frame and you can only put the skid as high as the tcase, unless you put a few bends in the skid, to work around the tcase hanging down).
So my vote is bucket, kong, or zor snatch.