Its a German channel, but I would throw Simplicissimus into the ring. They always had high quality content, and the quality of their videos is constantly rising.

They also have an English channel

Mustard Stories about Planes, Trains and Ships with amazing animation

Calum Scottsman on an Island talking about History and Arctic Exploration Vehicles.

RedLetterMedia

They used to do the Mr. Plinkett reviews and still publish a bunch of videos of reviewing movies that are very, very good (and entertaining) and other movie related content. While there are no more Mr. Plinkett reviews, they have maintained the same high quality of the channel for the last 15+ years. They just don’t publish content as often. It’s down to once or twice a week now.

Benn Jordan

https://youtube.com/@bennjordan

If you are into sequencers and drum machines then for sure Captain Pikant

https://youtube.com/@captainpikant

Forgotten Weapons

The USCSB has a channel with breakdowns of chemical disasters

It's got a pretty fun cult following and it posted within the last week XD

Phil DeFranco is better than he used to be by a long shot. He's getting senators and journalists in interviews for all manner of new related content. And he stopped with the enlightened centrism angle he had for a bit. Much more mature and level-headed.

Hard for me to say because over the years I've lost interest in most channels I watched years ago.

BobbyBroccoli, NightHawkInLight and Technology Connections are three that I always watch every time I notice a new video.

Techmoan is one of those that I watch from time to time.

And Nerdwriter1 is one that I haven't watch in some time but it is hard for me to imagine it having a decline in quality.

Joe Pera, comedian started around 14 years ago

nobody, musical mixes/tracklists, really good at setting moods and introduced me to a bunch of artists and songs 4 years of mixes

Townsends, classic pioneers time guy, mostly food I don't know how long but he's been around forever

Jeff Gerstmann, video games journalist

Mighty Car Mods are a pair of Australian blokes who have been doing car-based videos for 15+ years. Everything they've done has been high quality and entertaining.

I honestly don't know how they do it.

Overly Sarcastic Productions, consistently producing animated essays about history, mythology, and story tropes

I echo a lot of the sentiments here. Two I'm not really seeing are Project Farm and Eric the Car Guy. Eric is just coming back from a hiatus of sorts.

A few others I like

CNC Kitchen

Rob Dahm

Low-Buck Garage

Zach Freedman

SuperfastMatt

StrangeParts

Driving4Answers

CrackerMilk

PixelPete

Andy Didorsi (not as old a channel though)

Mr Carlson's Lab

Heather Cox Richardson

And of course, Technology Connections and Gamer's Nexus.

Bonus item because I like what they are doing, Edison Motors.

Music bonus item because she's remained consistently excellent for years, Lauren Babic.

If you like reviews/comparisons check out Project Farm.

Bad Obsession Motorsport ! I've been watching them build a Mini rally car for 12 years. They keep getting distracted by perfectionism and I'm very here for it.

Michael Reeves. One video a year, making the dumbest most hilarious shit you can think of.

some of my faves:

k&j lumber

project kamp

martjin doolard

m. bjornstroem

technology connections

this old tony

wesley treat

pask makes

frank howarth

chest’er

four eyes furniture

shawn boyd made this

James Hoffman, it even keeps getting better with time. The prophet for the coffee fans

For gaming content, I've been following CallMeKevin for several years. His stuff is always a good time.

Veritasium.

Patrick H Wiiems does amazing film commentary, but don't call it content.

Vlogbrothers ftw

Captain dissolution

Corridor crew

Crash Course

Some more news is still as it ever was

Gaming Historian comes to mind. (Caveat: he's no longer doing YT full time, so the uploads are a lot less frequent.) Anyway, he started out as the kind of prototypical kid with Youtube videos, doing a pretty well with the history angle. But over time evolved into a serious documentarion doing top-notch work. Along the same line, DidYouKnowGaming went from an ok channel that repackaged pretty common trivia into interesting but almost click-bait videos, into now being an investigative journalist kinda thing, where they semi-regularly share previously unknown information about old or cancelled games. Still on the games side, Electric Playground has been going for like a quarter-century, since back when it had to be on cable TV instead of Youtube, and Victor Lucas still doesn't suck.

3Blue1brown and Ben Eater make great technical educational videos that, as far as I'm aware, haven't really degraded.

Here's a range:

Sebastian Lague - game dev and software dev exploration

Pitch Meeting - film summary in short satire comedy form

Sick Animation - fucked up animations

Will McDaniel - comedy sketches using practical effects, puppets and fx makeup

DefendTheHouse - gaming myth busters and community content

FunWithGuru - showcasing easter eggs in games