This does come with a caveat, which is most television program tends to be liberal while most talk radio tends to conservatives. It makes sense given the demographics of these respective ideologies, and the media seems to elect to appeal to the segments where their market or viewers are located.
I believe that taken as a whole, the media tend to be biased in favor of liberals. In addition to the mainstream media, there is plenty of content focused on making fun of conservatives (i.e. the Daily Show), but not anything substantial poking fun at liberals. There are exceptions of course, such as Fox News. But more than any political bias, I think the media is focused on creating content that people will watch/read, even if it distorts the truth.
I believe the majority of news stations and newspapers have a liberal bent in the United States, there are some conservative television networks such as Fox News but they are far out numbered by liberal networks, I believe the majority of the media wants to influence the public to think more liberal minded as opposed to conservative minded.
Naturally the media would be more in favor of liberals.The media is seen as the watchdog for government and other large institutions.This is much more like a liberal standpoint because they are more likely to be critical of government and not just be the mouthpiece of the administration especially in times of war.
There is a huge myth buzzing around conservative America, and that is that the media bias is in favor of the liberals. What they so begrudgingly call "The liberal media." But the fact of the matter is that there are two major news network that lean right (FOX, and CNN) and there are more conservative talkshow hosts than there are liberal.