I would not say I have a favorite but I certainly have several that I prefer over others. I have a few computer related, a few tech related like phones, and a few for music.
I don’t watch YouTube very often.
One of my doctors suggested that I adopt a Keto diet, and she recommended a couple of people to watch on YouTube.
I’m not going to adopt a Keto diet, and I’m not going to watch her recommendations.
I don’t think that having a high fat diet is healthy for my heart.
I know that people can lose weight with a Keto diet, but I’m not overweight, and I just don’t think it’s a healthy choice.
(Sorry for the off-topic, but it’s just something that I’ve been thinking about lately.)
I am interested in what YouTube channels others like, though. 
I agree, I have heard bad things about Keto.
No opinion on Keto, but re: YT channels, most/all of the ones I watch are music-related, and I usually let them play and go do something else.
I have next to zero patience for watching reviews etc, for these kinds of material IMO nothing beats the written word + good pics, so I don’t subscribe to any channels of that sort.
I thought of a YouTube channel that I like!
If you like fractal zoom videos, this channel has some really good ones.
In another thread, I recommended three of my favorite fractal zoom videos which are all done by Maths Town.
I like those dashcam videos, workplace stuff, lawyer stuff, look-wut-i-made stuff, etc.
Dunno if any “favorites”, but a bunch of subs that I check out when I can.
This guy has a wonderfully eclectic selection of video topics, extremely knowledgeable about everything, no gimmicks, with clean language and presented in impeccable British English:
Agreed, if I want to watch videos I’ll go to Youtube, but I hate the self-serving prioritization that Google gives to Youtube videos in their search rankings. This is despite Google having a dedicated “Videos” tab for search results if videos are what you’re explicitly looking for, but no, they also have to shove them in your face in general searches.
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And for some reason, Marques Brownlee does the best phone reviews. He should be doing flashlight reviews as well.
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Project Farm - Great testing of real world objects.
This Old Tony - Machinest and tinkerer, and great dry humor
AVE - Colorful canadian who tears tools apart
Abomb - Machinist
Smarter Every Day - Great science guy, digs into some interesting topics
Mark Rober - Awesome science channel from a former NASA engineer. Real world and relatable. His squirrel course was a fun video, as was the worlds larges nerf gun.
Veritasium - Another science guy. A wind powered craft that can travel faster than the wind thats powering it? Yeah, that one is interesting.
The Action Lab - more science
The Slo-Mo guys - Blowing stuff up, in SLO-MO!
Linus Tech Tips - Computers and tech, high quality content
Unbox Therapy - Electronics reviews
Taufledermaus - if you like weird bullets tested
How Ridiculous - Things dropped from high places
ChrisFix - Car Repair
Jay Lenos Garage - Jay Leno on cars, need i say more
Various channels i have seen over the years that i like. I dont regularly watch any, except maybe this old tony, but all are high quality productions
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GIFGAS
Shiey
Well produced travel videos with no regard for personal safety or laws.
Mostly antiquity stuff. History for granite is one of my favorite channels. Also, I like PBS spacetime. Such things.
My favorite ones are topnotchidiots and rosscreations. They are both prank channels which i enjoy very much from time to time
Some already mentioned…
This old Tony - Home machinist, very skilled and very funny.
Big Clive - Electrical engineer with a slant towards tearing down LED bulbs and consumer electronics. Also carbonates pretty much anything.
2 Stroke Stuffing - Swedish guy on a mission to build the most powerful 50cc 2 stroke engine ever. Some incredible home casting and experimentation.
Steve Wallis (camping with steve) - Canadian guy who camps in some unusual places. I don’t know why I love this channel, but I do.
Colinfurze - Inventor of mad things, including tunnelling under his own house.
Leepspvideo - All things Raspberry pi.
John Rogers - Incredible and informative walks around London.
1.) Harald Baldr
2.) Virtual Japan
3.) Stokes Twins
4.) MrBeast
5.) How ridiculous
6.) UNSPEAKABLE
7.) Shmee150
8.) FLASHAHOLIC
9.) Styropyro
10.) Carwow
From memory and scrolling my notifications etc a bit, so may have missed some:
Cars: Tavarish, Hoovie’s Garage, VINWiki, Aging Wheels, Big Car, Car Wizard, Hard Up Garage, Driver61, Aidan Millward, Doug DeMuro
Engineering: Real Engineering, AvE, styropyro, Technology Connections
Aviation: Mentour Pilot, Disaster Breakdown
History: LazerPig, History of Everything, HardThrasher
Finance: Pi-Fi (>1yr paying member 
, more than pays for itself in returns )
Lights: Cheule, FLASHAHOLIC
Other/General/Multiple subjects: Deviant Ollam, Half as Interesting, LockpickingLawyer, Tom Scott
+1 for FLASHAHOLIC