As far as I know, individuals, not large organizations dedicated to one political agenda or the other. Since it is not on your list of sites to read based solely upon what someone else says about them not your own reading and investigating your opinion that Zerohedge isn't reliable carries very little weight. When you take another person's word that a third person isn't reliable you're listening to gossip and not doing your own thinking.
The other reason Zerohedge is reliable is that they publish information from multiple points of view, and their reports are verifiable using a bunch of other sources, including the government's own financial reports and multiple financial analysts and economists, who have done their own investigating and independently confirmed what Zerohedge publishes. They are not using circular reasoning like many leftists sites do.
By that I mean that one leftist site will publish something and quote someone who reports the same thing and quotes someone else. By the time you get done tracing their sources the last person's reporting is using the first article you are investigating as their source. In other words, they are using the same source for all their reporting but making it appear as if their report is verified from multiple sources when it's not. It all flows from the exact same source. They use their "sources" to create the illusion of multiple streams of thought but that is not the reality.
The criticisms of the mockingbird media are based upon deceit. Look at their reporting that the coronavirus is a bioweapon. They were the first news site to report this. The mockingbird media went crazy saying zerohedge was nuts. Well, it is a pretty well accepted thought now that zerohedge's reporting was 100% accurate. This is typical of the mockingbird medias criticisms of zerohedge. They scream foul at what is actually proven truth. They do it because zerohedge contradicts the mockingbird media's chosen narrative. And that is what real reporting is. It's looking at an issue from all sides and just reporting facts, not just an accepted narrative.
I have read zerohedge for years and for the first year or two would research everything they published to see if it was true. I don't give my trust to another person/organization easily. But after I verified their reporting time after time after for a year or more I began accepting the truth of their reporting. Now I only investigate stuff I don't know about to see if they are telling the truth on that subject. And I haven't caught them in a lie yet. Their reporting is very solid and truthful.