Although he isn't without controversy (seriously, ask him about the Rhodesians), Ian "Gun Jesus" McCollum of Forgotten Weapons is an absolute treat. He'll give you the entire history behind the making of whatever rare firearm he showcases, in a very Bob Ross sounding voice, he's polite, and just downright pleasant to listen to.
Another gun YouTuber, Hickock45, does something similar, but is also an expert marksman, and will show off more weapons in action than Gun Jesus, as Forgotten Weapons is more like museum curation than an old guy shooting the shit about his cool guns at the range.
Also anything Chris O'Neill touches becomes gold. He's a good boy.
Li Zikai has a lot of really cool videos about her life as an essentially self-sufficient farmer in the Chinese countryside. She's hardworking and very sweet to her grandmother, and her cinematography and music is top notch. Her videos are really good to relax to.
This guy has such an awesome set up that I've always dreamed of having if I got rich. I legit got sad when one of his ant colonies got wiped out by blood sucking mites. Comments in entomology videos are always so awful though. Its fun watching how enthusiastic he gets over ants.