Y'know, I hesitated. I admit I'm somewhat ambivalent about VSauce, because Michael's somewhat wandering style makes it closer to entertainment than the usually more focused topics the other channels on my list work with. That said, Vsauce is definitely interesting and great for fostering curiosity and an inquisitive mindset.
Also his new channel DONG ("Do Online Now Guys"... wut?):
Also his new channel DONG ("Do Online Now Guys"... wut?):
https://www.youtube.com/channel/UClq42foiSgl7sSpLupnugGA
Also I should've mentioned Veritasium:
https://www.youtube.com/channel/UCHnyfMqiRRG1u-2MsSQLbXA