I'm also a big fan of casually explained and exurb1a. my picks would be:

• CGP Grey - for his intricateley researched fact videos
• economics explained - clues in the name but makes a very boring subject and somehow produces extremely interesting video essays explaining the successes and failures of various economies and situations.
• crypto daily - cmonnn
• Thoughty2 - more well researched fact videos with a charismatic presenter
• John Michael Godier - fact based speculation on space based science and extra terrestrial life. Also has a brilliantly soft speaking voice, great if you're trying to get to sleep.