By topic, in order of how likely I am to immediately click on their video if I see a new one:
D&D:
• Viva La Dirt League D&D
(Including hammy greenscreen reenactments! Beyond hilarious. Top of the list. My god.)
Skits:
• Viva La Dirt League (gaming)
• Dr. Glaucomflecken (medicine)
• Ryan George
• Paint (parody music)
• MTGRemy (Magic: The Gathering parody music)
• Brian David Gilbert (music)
• Fire Department Chronicles
• Steven He (being Asian)
• Daniel Thrasher
Interesting/horrible facts:
• Casual Geographic
• Tom Scott
• Kurzgesagt
Movies:
• Pitch Meeting
• CinemaTherapy (psychology of movies)
Psychiatry (gaming bent):
• HealthyGamerGG
History:
• Tierzoo (prehistory if it were an MMO)
• Linfamy (Japanese)
• Fall of Civilizations (all 1-3hrs long but great)
• Townsends (US colonial)
• Shadiversity (medieval)
Gaming:
• The Escapist (zero punctuation)
• JelloPlaysGames
• Razbuten (highly recommend checking out his "Gaming for a Non-Gamer" series)
Art (chill):
• Sultan Sketches
• LavenderTowne
• ABD Illustrates
Art (tutorial):
• David Finch
• Bobbo Andonova
• Winged Canvas
Misc:
• OwlKitty (cat greenscreened into movie trailers)
• Exurb1a (emotionally distressing prose)
• LegalEagle (lawyer drama)
• JelloApocalyse (misc/gaming, can genuinely recommend the hilarity of a video about lemonade reviews, of all things. His delivery is fantastic.)
• b2studios (programming fun)
• Huggbees ("How It's Made" parodies)
• The Onion