Lemmino hits 1 and 3, and sometimes 2 (some of his videos are about dark topics, some are more fun or wonderous). His voice is very nice to listen to. Smooth, low, and a relatively thick, but perfectly understandable Danish accent.

To boot, he's one of the best goddamned researchers I've ever seen. For example, he did a documentary on Jack the Ripper. Instead of just going over the same beats everyone else does, this madlad poured over dozens of police reports, newspaper clippings, and eyewitness accounts from the time of the events, (more than 150 years old), and then compared those to more contemporary research to make a more complete study. He somehow put all of this together into the most cohesive description of the events I've ever seen, all with detailed and accurate CGI visuals (nothing graphic, just to show locations and timelines and such).

Really, really dedicated guy with a huge amount of integrity in his work, lots of creative flair, and no annoying biases or wild assumptions.

Vi Hart is calm and mathy. Here's the story of Wind & Mr ug.

Northernlion, specifically his non-twitch content. I also enjoy his twitch content but he goes reaction mode for it and it's not the same rhythm

My current go-to is Paul Cooper's Fall of Civilizations Podcast

StezStix Fix has a soothing channel where he fixes electronics.

I listen to my favorite British game show (QI and "8 out of 10 cat's does countdown") or the 10 hour loop of Joe Pera talks you to sleep https://youtu.be/91wX0NRjJqg?si=aMDe0U0oyoNmAbVR

For gaming I'd go with 'Midnight Snap' long let's plays designed for being on while you sleep. No shouting, no loud laughs or anything, just chill rambling

Not a "youtuber", but Jason Stephenson - Floating Amongst Stars might help you.

Hardware Haven is very calm and articulate. His (home made, I think) background music is really zen.

https://www.bbc.co.uk/sounds

Especially their podcasts and audio dramas.

I go to sleep with the History of Philosophy: https://podcasts.apple.com/au/podcast/history-of-philosophy-without-any-gaps/id396903391.

Everyone has different things they want for going to sleep, and this might not be right for you. But for me this is perfect because:

• its just the right level of boring. If it were any more interesting id stay awake to listen, if it were any more boring I’d turn it off.
• its not multiple people talking, because my brain thinks it needs to stay awake to be part of the conversation.
• i cant do video, needs to be audio.
• his voice is reasonably relaxing.

I seriously can barely get through 1 or 1 episodes before going to sleep. Another similar one is Dan Carlin’s Hardcore History.

I like ! He's a Dutch fella that does videos of him playing Doom levels with live commentary, all done in single takes with no saves. He also does Doom analysis videos, which are fantastic deep dives into the code and mechanics of the old Doom games, but I love his play throughs as sleep aid since he keeps the game volume low and has this low, soothingly calm voice and laid back quality.

Whisky.com! Smooth, German! Very serious about quality whisky.

https://m.youtube.com/@sea_space

This one is my favorite. It's mostly 30 minute videos about astronomy. I recommend starting with the newer ones.

I like brutal moose, he has had a whole slew of different content through the years from video games, cooking and shopping outings that are all funny, meanwhile his second channel moose2 has streams that are calm and great to sleep too.

Real calm voice, jazz in the background usually, still entertaining. Just don't put on any point and click adventure games to go to sleep because all the noises will be clicked repeatedly lol.

Manlybadasshero

Dude does a lot of indie games especially horror. But his voice is really soothing and he's really calm so I end up falling asleep a lot

The Librarian for me, no competition. He analyzes horror games/stories so well and the dude has a very pleasant voice.

Warlockracy, but I don't think that's normal.

Wristwatch revival is a go to for me !

Wolfpack345 plays naval war games and has a voice like that. He usually does slow and strategic submarine stuff. Puts me right to sleep.

Ozzyman reviews. I sleep violently.

Posy.

Dan Worrall

Have you tried ASMR videos? I'm sure there are lots of creators there that will hit all 3 for you.

Gopher, I found his channel learning how to mod various Bethesda games over 10 years ago but he has let's plays for various games that are great and put me to sleep when I'm tired

Don't know if they're on the tube, but I never made it through an episode of Brian Cox's Cosmos without nodding off.

Wirtual - trackmania streamer and ancient Egyptian expert

ChessNetwork

Northernlion for general gaming and PekinWoof for League of Legends gameplay are my choices

For me it has been Slay The Spire streamer Baalorlord. His cozy sub club is just too cozy for me some times.

No idea about YouTubers, but I sometimes put on Nemo's Dreamscapes to sleep. It's just a music ambience but I like it.

Biffa, he plays cities skylines and it's super relaxing