Climate Town - Does a decent job explaining climate-related topics and still makes them interesting.
Jay Foreman - Very funny map trivia.
JerryRigEverything - A bit too much promotion on some stuff, but really comprehensive tear downs.
MIT OpenCourseWare - learn good.
Pop Culture Detective - Deconstructive pop culture tropes that make you think a lot.
SNES drunk - retrogaming (not just SNES) but well done, 0% additives just prime content.
stacksmashing - electronics trivia and hardcore reverse engineering.
The National Gallery - If you're into history, this is an excellent channel about art trivia. I'm not much into art and this is always top quality for me.
Tom Scott plus - Tom Scott does British telly stuff like playing board games or chasing people on the streets with an apple tag.
Voices of the Past - This is slow, exhaustive history for nerds. Worth it if you want to let the story wash all over you.
Vox - slightly left leaning great journalism, albeit sometimes too brief to explain complex topics.
Weird History - They get some stuff wrong, but it's still entertaining.
Project Farm - Wanna buy an angle grinder? Now you do.
Insider - Had a series of "How Real Is It?" videos that let professionals describe stuff seen in movies, and it is both entertaining and a learning experience.
Corridor - Some stuff of dubious quality but if you're interested in FX, it's good.
LegalEagle - Law is hard, but is law fun?
brian david gilbert - Existential horror camouflaged as comedy.
PBS Space Time - Good but hard space science.
BurtBot - Orcs with normal voices.
Joel Haver - Neat if you're into deadpan humor.
Taskmaster - Probably some of the best british television available in YT.
Bonus round:
Practical Engineering - How stuff is built but explained well enough that even I can understand it.
Plus, use FreeTube, not You Tube. Don't be a slave of their terrible algorythm and all the recommendations will turn out to be of your taste.