For me it's DJ Peach Cobbler. I've been watching his videos since he had around 2,000 subscribers. Now it's nearly 450,000.
He used to mostly make videos on games, now he does a lot of history stuff too. He also has a little satirical news show, and a few tasteful shitposts. A really diverse YouTube channel.
What's your favorite YouTube channel that's not a mainstream big-name like pewdiepie, mrbeast, ksi, etc...?
Inside China Business
Its a chauvinist doing 10min reports on China's business practices. Its mostly a guy presenting well researched information about how China is eating the us' lunch and being frustrated about it.