All my favorites from Discovery channel are great - Dirty Jobs, Mythbusters, and Build it Bigger are great. Especially the graphics on Build It Bigger - some of the best HD I've seen.
It is a hit or miss with Mythbusters, Buid it Bigger and Dirty Jobs. As someone commented before, some of it is SD upconvert and some shows are HD but also some are shot with cheap HD equipment because the scene do not look at all like the best HD I have seen.
The same happens with Blue Planet on Science HD. Great program when it is HD but some of it also may be a combination of good HD equipment and cheap ones.
On animal planet hd, Wild Kingdom is very good when it is HD. I have not watched anything on TLC HD. Most of it is upconvert. MHD have provided some good videos but lots of their videos lack luster. Either they are upconverts or cheap HD equipment or technically they are doing something wrong. I watched the James Brown concert and it was excellent. I have not seen anything else that interest me there.
Versus is just a waste of channel to me. I do not follow hockey or golf or anything they have on it. So far it has zero interest to me.
Do not get me wrong when you put all these channels with a few hd programs here and there, the DVR becomes very full and and USB archive is imperative.