Computerphile — computer science twin of Numberphile; neat videos about the field with a wide range of guests.
EthosLab — pretty much the only Minecraft creator I still watch; witty, quiet and virtually the same for a long time.
hbomberguy — well known video essayist, easily one of the best in the platform
Jacob Geller — another quality essayist, exploring different themes, such as horror
Lemino — very well known creator focusing on mysteries, with incredible narration and stunning visuals
LockPickingLawyer — very simple, to the point and informative channel about locks and lockpicking; also virtually unchanged for years
Oversimplified — great overviews of major history events and periods, with funny narration and visuals
Tantacrul — fairly unknown essayist on music, with well researched material and nice takes :P
Then & Now — possibly my favorite atm (alongside hbomberguy); extremely well researched and presented video essays about history, politics and philosophy; very underrated imo