I'm surprised you'd even question that. I'm not saying that liberal leaning news organizations are legit and right leaning ones are not. Like I said, the wsj or the economist are hard right and absolutely top notch for credibility in anybody's book. Those two only make one factual error maybe every 2-3 years. NPR isn't quite in that category. They're more like 1 error every couple months. Doing live radio, like live TV for Fox, is more error prone so you can't really expect radio or tv sources to have quite the perfect records of the major newspapers who have time to review every word carefully before it goes to press. But NPR is definitely very solid for factual accuracy.
Fox on the other hand literally rarely goes a single day without publishing a flat out falsehood. Sometimes they get caught several times in a single day. They don't even bother doing retractions or corrections the next day anymore. Their audience doesn't care whether they retract mistakes or not, they just want them to get back to the infotaining.
Again, it's not about how biased they are, I'm talking about factual accuracy. Murdoch owns both the WSJ and Fox. They have the same lean. But he markets the WSJ to the intelligent, educated, conservatives who demand honesty and accuracy, and he markets Fox News to a less bright, less educated, less well off audience. Fox News competes with Jerry Springer and Judge Judy for the dramatic psuedo-information audience, the WSJ competes with the NY Times and Foreign Affairs for the high end audience. They just do completely different things.
The left has similar outlets to Fox. Michael Moore, for example, I'd put in the same category as Fox. But to compare Fox with NPR just makes no sense. They're completely different tiers.