Bill Moyers is a more reliable journalist than Bill O'Reilly. Bill Moyers has a long and storied history as a journalist, and even served as a White House Press secretary under Lyndon B. Johnson. Contrary to this Bill O'Reilly bases his journalism on his own personal beliefs, and is more of a political commentator than a journalist.
Now, you shouldn't simply believe anyone - particularly anyone with a political agenda - but Moyers certain has more integrity. The network he works for has standards of factual accuracy to maintain, so Moyers cannot deviate from the facts. O'Reilly's network, on the other hand, does not adhere to a rigorous journalistic standard.
I believe Bill Moyers is more believable than Bill O'Reilly. I believe O'Reilly tends to be more biased and more outspoken on his beliefs even though a lot of people don't see eye to eye with him. I think he is also fairly bad at deabting situations and usually tries to work around it.
I believe Bill O'Reilly more than I believe Bill Moyers, because O'Reilly is from a working class background. O'Reilly wants to get the government to tell the truth and be accountable. Bill Moyers is just the opposite, and he has been part of the political machine ever since he was the press secretary for LBJ.
I would believe Bill O'Reilly more that I would Bill Moyers, just because I think that Bill O'Reilly does a better job of getting his points across, and since he seems to have better ideas that he can back up with true fact and not just his opinions on things.