I'll chip in with some channels that haven't been mentioned yet
Sam Aronow does Jewish history from prehistory onwards (we're currently in the middle of WW1). I find him to be an engaging storyteller who takes the history seriously and doesn't attempt to make it "fun". The episodes also feature fantastic custom-drawn map of cities.
Asianometry does videos on IT history, Asian history, and Asian IT history. Presentation is a bit dry and technical, but you can learn a lot about some of the more obscure bits of history, like the history of the camphor trade in Taiwan, or the rise and fall of the Bulgarian computer industry.
Fascinating Horror covers various natural and manmade disasters in ~10 minutes long videos. The delivery is matter-of-fact, there's no sensationalisation, the stories themselves are interesting enough.
Historia Civilis features deep dives into mostly the end of the Roman Republic (plus some other stuff) accompanied by simple but charming animations and lots of maps which I always like. Uploads are once in a blue moon but there's a large archive.
Voices of the Past is a guy reading a bunch of primary sources, eyewitness accounts of everything from Ancient Greeks describing India to Cherokee envoys in England to Soviet tourists in 1930s America.
Soup Emporium rarely uploads and there's a grand total of seven videos on the channel, but they are good. In particular, the one on Chernobyl, the one on Koko, and the one on Helen Keller.
Imperial talks about various historical topics with a focus on the 20th century, the graphics are fancy but I just like the stories and the way they're told.
Sean Munger is one that I've come across recently, has a very large library of videos on various topics from the Gulf War (1991) to various maritime disasters to US presidential elections. Style is "guy talks into a camera for fifteen minutes to three hours".
Premodernist only has 19 videos so far and I'm posting it here mainly because of the video on time travelling to medieval Europe. I like his style and here's hoping for more content.
Rare Earth is more politicised/preachy and sensationalised than the other ones I've talked about, but Evan Hadfield is good at it. He films on location and tells interesting and/or obscure stories in nuanced, thoughtful, and sometimes heart-breaking ways. New uploads are rare these days but there's a sizeable archive.