I don't have any reason to watch CNN so I really don't know if it is that they are bias, or that it is impossible to actually report on the Republicans and not come off as bias.
And as for Maddow, she's MSNBC, and I would argue that she actually does a decent job keeping her rhetoric in check about the crimes that have been going on the last few years. There is only so much you can do to not let emotions seep through when dealing when talking about things like our mentally abusing small children for years.
Or deporting retired vets. Or banning trans people form serving in the military. On and on.