Do you have any favorite YouTube channels?

Not mentioned that I have seen is the Ben Heck Show, that dude can hack stuff.

Gaming related:
XboxAhoy (nowadays only Ahoy) - produces the highest quality gaming content I've found on youtube.
Day9 - although I only watch his Hearthstone videos he's probably the warmest, chillest streamer/youtuber you'll ever find.
DidYouKnowGaming - has a lot of retro (mostly Nintendo) content in form of Mario and Zelda, you always learn something new when watching their vids.
Egoraptor - not very active but great animations and pretty good songs.
Escapist - Zero Punctuation, the flagship of the Escapist, ran by Yahtzee Croshaw who through very vulgar descriptions shows his distaste (or liking) of video games. (He also coined the term PC Master Race.)
EthosLab - best Minecraft content there is. I strongly recommend his single player series if you enjoy minecraft.
StrifeCro - one of the best hearthstone players with great live analysis and commentary.
Super Bunnyhop - the best gaming journalist on youtube. Well articulated and explained reviews with a lot of research behind it.
That One Video Gamer - otherwise known as the completionist. Reviews of games played to 100% completion.
The Game Theorists - formulating theories around video games through qualified research.
Totalbiscuit - pretty good games journalist showing off lots of games.
Trolden - montages of hearthstone plays.
Trump - mild-mannered hearthstone player, not as good as StrifeCro but he does F2P runs sometimes.

Non-gaming related:
BroScience - great content, I find that I always laugh when I watch his videos.
CinemaSins - nowadays he really nitpicks and grasps for cheap sins but his earlier sub 10 minute ones were great.
Don'tBeThatGuy - funny short films, they haven't been active for a long while but I'm still hopeful that another video might come out some day.
ExplosmEntertainment - Cyanide & Happiness shorts.
How It Should Have Ended - animated shorts about how movies should have ended.
Kassem G - does funny reporting, recently became active again after a long break. His Going Deep series was absolute gold.
KRNFX - master beatboxer, makes great high quality covers.
LastWeekTonight - the best and most entertaining news show on- and offline.
Minutephysics - not frequent uploads and his earlier content was better but overall great short videos explaining physics.
Simon's cat - cute shorts about a cartoon cat.
Ten Second Songs - amazing vocalist who covers songs in the styles of other musicians. Everything from the Andrew Sisters to Pantera.
The Film Theorists - formulating theories around films through qualified research.
ViHart - explains music and notebook drivels by using math.
Vsauce - explains various cohesive scientific theories and phenomenon through well-made explanatory videos.

CrazyRussianHacker : https://www.youtube.com/channel/UCe_vXdMrHHseZ_esYUskSBw
ExplosmEntertainment: https://www.youtube.com/channel/UCWXCrItCF6ZgXrdozUS-Idw

DreamcastGuy
BirgirPall
Escapist
Derptlemen
mans1ay3r
Jim Sterling
AngryJoeShow
stevecash83
Tiger Productions
Krzysztof Smejlis
zefrank1
Ricepirate
mashed
Flashgitz
How It Should Have Ended

Robbaz king of Sweden. 'Nuff said. Seriously though, Robbaz plays random games, he has a few series continuing like Sims 3 which he has taken beyond anyone ever has and some other mini-series. He's pretty funny and doesn't upload frequently because of being busy, but that means time to watch and catch up on his stuff easier.

BORBOBtv, reviews of some old games and short videos about awesome people. :)

Gaming

Birgirpall - Hilarious, I love the "We Broke" videos.
TotalBiscuit, The Cynical Brit - Great reviews, mostly. When I want to know about a game, the "WTF Is..." videos are neat.

Music

(All electronic music)
xKito Music
Monstercat
Diversity Promotions

Comedy / Other

Bad Lip Reading - Greatest lip syncing comedy channel I know. This is one of the best.
CorridorDigital - Awesome channel with lots of short clips. Mostly focuses on playing with visual effects.
PurpleEyesWTF - Somewhat similar to Bad Lip Reading in a way, this guy takes anime and voices them over. The results are simply hilarious. (Please watch the Code;Geass abridged series called Code;MENT... It's worth it.)
JonLajoie - Just found it recently, doesn't quite go into music since it's lots of satire and comedy songs, but yeah, it's music.

My favorites:

I Hate Everything - Rants/Comedy
A Dose of Buckley - Rants/Comedy
Epic Rap Battles of History - Comedy/Music
Linus Tech Tips - Technology
jacksfilms - Comedy
MKBHD - Technology
videogamedunkey - Gaming/Comedy
Channel Awesome (Nostalgia Critic) - Movie Reviews
The Dom - Movie Reviews
DouchebagChocolat - Anime Reviews, Comedy
Chris Stuckmann - Movie/TV/Anime Reviews
Rob Dyke - I honestly don't know what he's classified as :P
Filthy Frank - Comedy
Screen Junkies - Movies
Total Buscuit - Game Reviews, Gaming
Animenz - Anime Piano Covers (brilliant playing, inhumane ability)

Haven't seen him mentioned... I may have looked over it if there is, but...

GoldGloveTV - My favourite youtuber, been subbed to him for around 3 years now :D

https://www.youtube.com/user/HardwareCanucks
https://www.youtube.com/user/markiplierGAME
https://www.youtube.com/user/theRadBrad
https://www.youtube.com/user/unboxtherapy
https://www.youtube.com/user/JimmyKimmelLive

AlphaOmegaSin
The Heavy Metal Gamer
Count Jackula
GoodBadFlicks
The Irate Gamer
Lazy Game Reviews
Ahoy (Used to be XboxAhoy)
Coolduder
ProJared
HappyConsoleGamer

Vinesauce Joel is pretty good. My favorites are the "Windows destruction" series.
PeanutButterGamer
AngryJoeShow

That's all i got right now

Mostly spanish channels and totally related to games I would recommend: DidYouKnowGaming has very interesting facts about games and some of them aren't the typical ones you read on the internet, elrubiusOMG hilarious random gameplays in spanish, DrossRotzank really interesting tops in spanish normally about "strange" things...And more like gameranx, alexBY11, Xodaaa, Caith_Sith, The Slow Mo Guys, Pewdiepie (love it or hate it),etc.

They've already been mentioned, but definitely check out BirgirPall!

I recently started to watch Marshall Dyer and his LPs. He's not the loud-ass energetic type usually found among LPers, but still manages to be funny and entertaining; his commentary is equal parts goofy and thoughtful. And I really like his choice of games. And that soothing voice ;).

I like The Game/Film Theorists and also Zero Punctuation over at The Escapist.

I'm partial to Chuggaaconroy, Smooth McGroove, Tsuko G, Treesicle, ProJared, and Game Grumps.

I absolutely despise The Game Theorists. The way MattPat kinda sneers with every statement just grates on me.

Actually I watched some Argentinian youtubers a pair of years ago, but I switched to twitch/gameplay youtubers, so I can't help you :/
I remember maritokids, alfredito, dross, metal warrior, mistered17, ... all that band.

The Criterion Collection, Every Frame a Painting, The Examined Life (of Gaming), Matthewmatosis, Noah Caldwell-Gervais

UberHaxorNova
Markiplier
Videogamedunkey

And for videogame news:

IGN
Machinima

And for random/ funny stuff:

Fine Brothers Entertainment
Smosh
Nigahiga
theDOMINICshow
Epic Rap Battles of History

So if you are into gaming (GTA V, MC, Rocket Leauge) Look at a group of youtubers called "The Crew," which comprises of:
KYR SP33DY
JahovasWitness
Sidearms4Reason
ShadowBeats
NobodyEpic
G18SprayAndPray (better known as just G18)
Deluxe 4
Deluxe 20

KYR SP33DY is the best to look at first, mainly because he is pretty diverse in games and reactions.
(these are all of their names on YT, just look them up.)

TheHybridLibrarian.

Has anybody mentioned Hot Pepper Gaming yet? All you'll ever need :)

vsauce is pretty nice

https://www.youtube.com/watch?v=f8WsO__XcI0