Being a nerd, geek, and engineer, my favorites fall in pretty much those categories:
Mark Rober puts out consistently great content.
Puffin Forest tells stories of DM/GM'ing tabletop RPG sessions
And if you want some really, REALLY great content that addresses issues with Youtube,
Nerd City has the BEST videos that go into insane detail about a wide variety of topics. Their latest video talks about Youtube and their hidden dictionary of demonetized words, going as far as to feed it over 15k words and seeing which ones are and aren't auto-demonetized.
Tom Scott has a series called "Amazing Places" and "Things you didn't know" that are both incredibly informative about the world around us.
For a little weird Youtube,
Jackson Crawford is a Ph.D lecturer and noted expert in Norse Mythology and language.
Can't leave off Gun Jesus, aka
Forgotten Weapons
And for all of you who enjoy a little schadenfreude, there's
SciManDan, who takes on conspiracy theorists and flat earthers, and
Kitboga, who does "IRL" streaming of him prank calling the IT Support scammers. If you enjoy watching someone spend hours wasting someone's time with a complicated series of fake websites and virtual machines, watch Kitboga. Seriously. It's hilarious.
Oh, and
ThisOldTony and
AvE both get my engineering needs satisfied.