Bobby Fingers. He makes diaramas of weird things and then buries them in the woods for people to find. Doesn't make videos too often but they're hilarious.

Kyle the Scott. A Scottish cisman with a kinda effeminate voice who once did a dramatic shirt rip to prove he is in fact cis, in the middle of a half hour essay about why it shouldn't even matter and "transvestigations" are bullshit.

But his normal schtick is media criticism, covering franchises like Star Wars, Halo, and Assassin's Creed. They're just genuinely good reviews that aren't afraid to get into the politics where appropriate (including explicitly rejecting some of the more popular bigoted takes) but honestly feel it's about the way that particular lens affects the media, rather than being an end into itself.

A really tiny channel I like is Don't Look East. Currently less than 3000 subscribers and most videos just get a few hundred views. He does unscripted travel vlogs about rarely visited destinations, mostly in Asia and Eastern Europe. For example he recently travelled the entire Thailand/Myanmar border by motorcycle.

My husband recently found this gem of a cooking channel that we both love. Chef Jean Pierre He's hilarious and the food looks amazing.

Matt Brown - security researcher and bug bounty hunter

Robert Murray Smith - general mechanical engineering tinkering, lots to learn

TheCod3r - console and other electronic repairs

Wesley Kagan - builds cars but is just an overall genius and entertaining

Joe Grand - hacker, genius

There are more popular/sometimes better people and channels in each genre but I've stuck to those with under 1 million sub's. I'll assume people like Colin Furze, Ben Eater, Computerphile are already too well known for this thread

twoodfrd - the guy repairs guitars with his soothing voice and lots of technicial knowledge

Fresh from the Farm Fungi - he is a mushroom farmer from Colorado. He has a ton of valuable information on growing mushrooms and running a business. He also has a few series of videos on very interesting experiments such as growing boletus, morelles, and cordyceps.

Microbehunter - he is a biology teacher that runs a microscope channel. His videos are very useful for learning the basics of microscopy.

Huygen Optics - I'm not sure about this guy's background. He worked in R&D for Phillips in the 90s and he knows a lot about optics and chemistry, but I don't know much more. He has built some equipment in has garage for sputtering metals on surfaces and has some pretty cool videos.

MissOrchidGirl - she is more popular than the others. She has great info about caring for orchids and a fantastic orchid collection.

Ben Felix - he is a portfolio manager with very solid financial advice. He supports his claims with research articles.

https://www.youtube.com/watch?v=xLfFWXUNJ_I It's more of one playlist than a channel about quantum mechanics on Russian, but as I see it has English subtitles. A fairly clear explanation with a small amount of simple mathematics, probably the minimum that is possible. It helps to understand at least a little such a complex and illogical science for the average layman.

Aussie Wood Shed

https://youtube.com/@FishingHistoricPlaces - Brief visits to places, mostly in New England, with interesting historic and natural history info. Rarely any fishing.

https://youtube.com/@EarlyMusicinadifferentway - talented multi-instrumentalist and composer playing early music and his own compositions and improvisations in an early music style. Interesting videos too.

This spanish guy makes videos about retro consoles, games and computers from Japan. The videos are pure info, without intro/subscribe/like shit. He changes the name of the channel every few days so maybe this link will be dead soon: https://youtube.com/@conpostersdetiasenlapared

DuskTillShawn

Does mostly just kinda essay like videos going over cartoon episodes (or even whole characters in the case of Hey Arnold!). Seemingly just nickelodeon right now, though there are others like a CtCD video.

Don't feel as out of place sharing a 159k sub channel when OP brings up a nearly 450k channel.

Also, this post motivated me to look through my subs and found a couple I unsubbed to and found some shocking things like some channels last videos were more recent than I thought. Also keeping myself away from going on a nostalgia trip of over a decade ago.

https://www.youtube.com/@epochphilosophy - philosophy channel with very well researched and produced videos

@PaddysBushcraft

@TheMapReadingCompany

@VideoTechExplained

Vindsvept, fantasy music https://youtu.be/ZDokgvuuS7E

Also I didn't think it was a small channel but apparently he only has just over 1m subs: Karl Jobst, he mostly covers video game speedrunning achievements and cheating https://youtu.be/AFrQ1_2bbsI

CGP Grey kicked me off on this intense obsession with getting rid of First Past The Post voting, but he has many other very well made videos. Cannot recommend him enough.

Notable runners up:

Steve1989MRE (let's get this channel out on the tray)

JoergeSprave ("welcome to the slingshot channel" evil genius laughing)

Campingwithsteve (for info on how to be homeless more effectively)