I love the concept of both shows: being out in nature, by yourself, doing whatever it takes to survive. It is so alien compared to what most of us go through on a day-to-day basis, and yet it is basic information that we should all know... just in case. It's sad that some people can barely survive one day without a cell phone and a credit card.
However, Survivorman is the real deal. He is literally out there by himself and has only himself to depend on. Because of this, he takes a more cautious, constructive, and efficient approach to his survival methods. He tries to avoid things that might make him sick or injured, unless he has exhausted all his other options. Bear on the otherhand show boats at every turn, doing ridiculous things that no one in their sane mind would attempt if their life was actually hanging in the balance. While Bear is wasting his time and energy and taking unnecessary risks, Les is resting up and pacing himself.
I think both men are top notch survival experts, but the Man vs Wild show is definately more geared towards entertaining the viewer with wild antics and Bear with his shirt off. Even though the obvious editing done in M vs W gets annoying sometimes and his methods are a bit unrealistic, I probably watch both shows about equally just because they are better than the rest of the crap that's on TV these days.