I've found the Chaos Gym really good. At least, it's on the rise and not fallen to the clickbait so many channels do. Quality content well presented so far. Probably my favourite right now. Proper meta stuff. Specifically interviews with players who made the top cut at any given regionals and why
their version of whatever deck is the one they went with.
Tablemon is enjoyable & informative (a difficult combo to pull off), but a bit much sometimes. He has a nice mix of genuine meta stuff but the little fun stuff like his pokedex of decks show a more relaxed side to the constant points chasing.
TeamFishKnuckles & YellowSwellow are long time two staples well worth looking at.
I enjoy DarkIntegral's enthusiasm but for educational purposes it is not great. Kind of unfortunate then, it is most new players first stop. Fun though, don't get me wrong.
I found a good one today - still only small about 15 videos - called "
Discount Pokemon Decks". He is well aware that the Meta Decks are covered by dozens of other channels so all his videos are his own random creations. A bit like DIG except he seems very aware that his builds are hit and miss fun decks and nothing more. He explains his reasoning for everything very well though, not that I always agree with it, but it is good to hear. That is the real hook.