I think the real problem is not that there is no "balance" and there are more "liberal" or more "conservative" pundits. This question is not even the right question in the first place. That's because facts are neither liberal nor conservative, but either true or false. And because quality does not depend on the leaning. The media is not supposed to tell people what they want to hear, but what's true.
As I see it, the most rampant bias is not a political leaning bias, but a bias towards simplification, polarization and personalization. Conservatives complained the mainstream media lacks quality and has a liberal bias, but instead of calling for a non-biased quality alternative, they got FOX News, which is just as dumb as the mainstream media, just with a conservative bias. The same thing, just algebraic signs reversed.
But a genuine quality report should not ignore facts when they don't confirm the views of those who watch it. A true quality report should name facts when they confirm the political bias of the audience, and name facts that contradict the bias of the audience alike. It should give credit where credit is due, regardless of partisan affiliation. And it should report background information: When a topic is complicated, there should be the time to actually explain it, instead of cutting it down to a few lines or catch phrases. And when a problem is systemic or structural, it should not be simplified by making it to the individual problem of a particular politician/official/party.
As I see it, the main problem is that mass media, especially TV but also radio, often doesn't have the patience to do that, but desperately clings to ratings. But quality reports don't necessarily bring good ratings. That's why they simplify and personalize, bloat up non-issues to lurid scandals, and tell their respective audience what they want to hear, rather than what's true.
The worst thing is this constant call for political "balance". It's absurd in the first place. That is because there are simply not always two equally valid stances on every problem. This satire exemplifies this problem (and may provide a little laugh on this topic too
):
My two cents.