Since I don't have cable I tend to pig out on TV when I visit my parents. Though there's not much in the way of brand/channel loyalty I did get hooked on a couple of Discovery shows, at least briefly.
Mythbusters is a great idea but over time the less-than-great execution has made it a bit tiresome. Putting all sorts of legends and hearsay to real-world testing can certainly "make for good TV" as They Say but the Mythbusters tend to pay too much attention to that and aren't as rigorous as they should be. An example is a show about whether a bullet shot into the air will fall with enough force to kill somebody. Their tests (some of which seemed too elaborate) showed no but a doctor who has specialized in such wounds says it in fact happens. They declared this one undecided but the real questions are were their tests actually testing this (and do we want to trust two special effects guys) and are the doctor's cases reliable (were there other factors). It's similar to a show where they proved that splinters caused by cannonballs on a wooden fighting ship couldn't cause the bodily damage that legend has it. Except they were completely wrong. Not doing the background research and then creating a test that overlooked key factors (in this instance velocity and type of wood mainly) were problems but ones that are typical of the show. When they're testing limited, narrowly defined myths it's fun to watch but they seem to be running out of those.
Survivorman was a real hoot when I first watched about six episodes back-to-back. The host seems to know his stuff and the self-shot/no-crew approach captures how such shows should be made. So this is what to do if stranded on a deserted island, or left in the jungle, or lost on a mountain. (Not that it really matters - 99% of us watching wouldn't be helped if we were in these situations in real life.) After a while, though, there's only so much he can do. Yes yes capture water, look for food, build shelter. The basics are more or less the same everywhere and the specifics aren't really different enough to support many shows. But those first shows are pretty cool.
Man Vs. Wild (aka Born Survivor if you're a Brit) is the same idea but gets nearly everything wrong that Survivorman gets right. For one thing, this host is an annoying creep and though he probably really is the ex-SAS survival expert the promos promote he might as well just be some actor (& if it's all a hoax it wouldn't be much of a surprise). Having a crew that's clearly tagging along behind him makes the whole thing seem even more a performance. In fact parts actually are since some deceptive scenes have been well-documented (and at least one so blatant it was cut from the US airing).
Part 2 - Dirty Jobs.