Good question, I'm not someone who likes to say that something is absolute truth as all truths are subjective. However, if I had to point out a few conspiracies that are a near lock - FLAT EARTH.
Just kidding, that shit is total crap.
I think one of the most significant things that has been established is media manipulation and CIA's operation Mockingbird. The CIA exerts significant control over the US media and has done so since the 1950s. With the rise of the internet, free flowing information, and alternative media (low cost) more people are becoming aware that the West has the most powerful propaganda ever created and our society is filled with illusions and falsehoods that most people never question. It's only going to intensify as Obama signed NDAA 2017 which legalized domestic propaganda.
Btw, I love watching Annunaki docs, but I too think that it's pretty out there. Fascinating to think about nonetheless. I find the idea that we're genetically engineered by an alien species to be a pretty mind blowing idea.