Anything (not a channel name, just anything) by Tom Scott, his recent gameshow has been pretty good as it's like Only Connect but I've got a better chance of answering the questions. Huge backlog of things too and as he's got more popular he's got more access to interesting places and things. Just seems like a genuinely nice guy explaining things he finds interesting. Probably worth starting with "things you might not know" or "amazing places".
CollegeHumor - can be hit and miss but the ratio is good enough for me. They did a series of a gameshow called "Umm actually" which was great.
Gus Johnson - never quite sure where I am on things going too far on these but it keeps me laughing and coming back.
exurb1a
ClarkeAndDawe - teaching me about Australian politics, one fake interview at a time. What got me into it: https://www.youtube.com/watch?v=3m5qxZm_JqM
Bill Wurtz - Ranging from absurd 5 second clips to, well, this: https://www.youtube.com/watch?v=xuCn8ux2gbs
CasuallyExplained