News and weather are #1, even news channels I disagree with. I watch a lot of international news, because US news is so slanted and lacking in world affairs. I have to watch Colbert and The Daily Show, not just because they are funny, but they come at the news from a different angle. They are often more reliable sources than actual "news" programs, and they serve as fact checkers for the big networks. Fox, CNN, NBC, etc, often overlook fact checking in order to be the first to air something, and don't dig deeper before opening their gaping pie-holes.
Next on my must watch list is documentaries that are relevant to me. It's a shame that a medium such as television, with its power to educate and inform, is wasted on such trite and mindless stuff such as "Honey BooBoo" and endless reality and talent shows.
I also like to catch "Dr. Oz" and "The Doctors", because they are informative and useful, even if "The Doctors" often blatantly show products of sponsors in a good light, and accept free products for giveaways. It is important to me to maintain my family's health on my tight budget.
One final show: COSMOS.