I can't be bothered to rate youtubers on "tiers" but this seems the thread to throw in some opinions.
First of all, yes I visit quite a few audiophile youtube channels. It's more driven by an interest in audio than any love of youtube audio videos. In fact I often watch them and wonder "why am I doing this to myself?" because I find a fair amount of irritation attached to watching them, less than reading reviews.
Most are grossly inefficient ways of gaining the information I want. And the worst are the latecomers, print magazines that have seen that "you have to be on youtube now" and so they are giving their try. The Absolute Sound's attempts at youtube videos are of this totally cringeworthy ilk. They just don't get it and come across like grandpa trying out Snapchat.
But, some comments, not necessarily ranked:
1. ASR's videos are I think among the most informative and important audiophile videos on the internet.
2. Zero Fidelity - hit and miss in terms of subjective reviewing quality, but mostly for me a bit hard to watch because of the ever-present smirk, ever present 3-D coming at me hand gesticulations, omnipresent cap, and general feeling of "guy at party who wants you to know his opinions." (None of which are incompatible with him being a perfectly good fella).
3. New Record Day - sometimes informative, decent video quality, somewhat irritating presence.
4. Cheap Audio Man - admittedly he deals with products I'm not interested in. Sometimes he can be amusing. Mostly it's too much "chip on shoulder" "look at what a rebel I am for liking cheaper stuff" vibe.
5. Audioholics - good info, generally good takes on stuff. I like Gene, he's a no-B.S. kinda guy. The videos can be a bit long and shot-in-the-basement quality.
6. British Audiophile - decent video production, smooth delivery, can be fun to watch.
7. Jay's Audio Lab - for pure audiophile pron. Fun to look at the expensive stuff. For audio information? Pretty much bereft of that. It's basically a guy who can somehow afford to go through endless varieties of expensive gear and thus considers himself a guru. Talks in a "too serious" way about everything "Guys...I'm sorry...but I just HAVE to tell you the TRUTH about this...."
8. OCD Hi-Fi Guy - dear god. Every opinionated audiophile and blowhard dealer I've ever met rolled up in to one character. Hard to tolerate, but still shows some cool gear on his channel. (And...again...not that he isn't probably a perfectly good guy..)
9. Audiophile Junkie - I actually like this guy's channel! He could have been an OCD Hi-Fi- like guy, but seems more chill and grounded, also at least a higher level of technical interest/skepticism vs the above. Though still deep in to the classic hi-fi audio territory, which is fine by me as I like that stuff. He does some of the best Audio Show videos. I've often watched them on my home theater system. Since they are of excellent video and decent sound quality, they can have a real "you are there" effect which is fun.
10. Jay's Iyagi - ugh! Again...one of those characters I just don't connect with and hard to watch - the super opinionated young dude dispensing audio wisdom.
11. Audiophiliac/Steve G - I have watched plenty of his videos. I think he generally does a decent job as a subjective reviewer type, and reviews a lot of gear that many audiophiles are interested in. Sometimes he seems to be struggling for words to describe things, making me think "wait, isn't this your job? Shouldn't you have the words to describe this?" So I can find his descriptions somewhat wanting. But, again, I think he provides a nice service to many audiophiles looking for that kind of channel, and he has plenty of fun interviews with audiophiles.
While I find that video reviews tend to be a very inefficient way of getting a reviewer's take on gear, I do find that a few youtubers HAVE managed to generally conquer the format quite well, such that it does feel like the video version is a bit richer than if it had been in print.
So:
12. Darko Audio - while slightly off-putting to me as a presenter (has a sort of aggressive look and tone), I do think he does a very good job as a sort of "everyman audiophile" giving his take on gear, as well as providing lots of information about the nature of the gear under review, how to set it up, what it's like living with it, etc. And the video production is generally very well done, looks great and tends to augment what he is saying. His recent videos detailing moving in to a new room with terrible acoustics (and showing measurements) and his follow up after acoustic treatment are VERY well done and kept me interested all the way through.
13. Andrew Robinson - Yeah, maybe a bit smarmy and too-chilled by a click or two...but he's mastered the format. He speaks at a pace that keeps the info coming, he gets to the gist of most of the relevant details about the product, gives nice descriptions and comparisons, and the video quality is nice for gear eye-candy.
ETA: Whoops forgot I wanted to mention...
14. Earspace - Jana Dagdagan has got to be the best videographer/producer for videos-about-audio-gear on the internet. Total finger on the pulse and beautiful presentations.
15. Erin's Audio Corner - I find Erin to pretty much nail the perfect balance between providing fantastic measurements AND also trying to correlate those to his subjective impressions. So I get both worlds. Plus I find him among the most watchable presenters of all - chill, humble, not obnoxious, just trying to get at the truth the best he can.
*(As you can see, a lot of my gripes about youtube reviews has to do with how I might find the presenter irritating in one way or another. But, hey, that's the digs you take when you take yourself to video. I'd probably annoy some people too if I tried it. In print reviews I at least don't have to look at the reviewer and deal with his/her personality as well as the review...)