Who's the most credible newsperson on television?

the vast majority of pundits and commentators (like sean hannity and keith olbermann and roland martin) follow party lines no matter the hypocrisy and irrationality. are there any tv-persons who overtly express their political opinions but maintain a reliable reserve of rationale and earnestness?

i am not referring to unbiased, bipartisan reporting. i am referring to a sound, consistent, and rational opinion-reporting—the person that can look at his party and say “wow, you’re incredibly wrong on this point.”