I'd look at the Kawasaki Bayou 4X4 300, or the Honda. Maybe a Yamaha Kodiak 400 if you can find one. The older shift machines are pretty darn reliable.
I used to have a Bayou 300 but it was a 2x4. It was almost bullet proof. The same thing in a 4x4 with a low range would have gone about anywhere. It was also light enough to be easily maneuverable.
