Practical Engineering - in depth presentations of civil engineering feats, concepts, problems, solutions

Joe Scott - just simple, entertaining discussions of interesting topics

Philosophy Tube - longer format, intensely well-cited presentations on philosophy related to current events (with theatrical costumes!)

Ryan Hall - who knew that a weather forecast could be so fun? Regularly updated weather forecasts for the entire United States with detailed coverage and livestreams of events like tornado outbreaks, hurricanes, and large snowstorms. With charity drives to provide supplies to people on the ground

PBS Spacetime, PBS Eons, all the PBS channels really

Plainly Difficult - consistent quality, often hilarious presentations of various disasters. I particularly like his entire series on radiological accidents, often involving lost radioactive sources that random members of the public stumble onto, which is terrifying.