As awful as it sounds, the most anti-conservative pundit on CNN has been David Frum, not Paul Begala or Donna Brazile. Frum literally foams at the mouth whenever someone suggests any candidate not named Mitt Romney. He especially hates Herman Cain. Gloria Borger is really awful as well, promoting Romney at the expense of the others.
Yes, Donna Brazile is actually one of the easier of the liberal pundits to listen to. She’s open about her own politics and she can give a worthy conservative his or her due. E.g., she’s spoken admiringly of Gov. Palin’s political skill for some time.