I have an MT OR and I love it, but I will say this: probably for getting around in tight spots offroad, especially with our inadequate OEM clutch, the AT is better. Once somebody designs an aftermarket clutch that won't fail after one or two high-rev slips, then it would be more of a toss-up. Our clutches are a weak link, no doubt about it.
I've also been surprised by the consensus in the offroad magazines and other publications that ATs outperform MTs on obstacles, in general. I'm an MT guy, but I'll pass that along, since I read it and hear it over and over.