Personally, I find YouTube to be unusable if you think of it as channel-based. What I do is keep a list of topics and perform a search based on the topics.
That pulls in some set of videos, of which maybe about 20-50% are exactly what I want. If the search yields no great results, it's usually because I've gotten the search wrong or the topic isn't well covered on YouTube yet.
With the kids, I don't talk about watching "YouTube", I talk about watching "learning videos" and if they want to watch a learning video, I ask them to tell me what they want to learn before we turn the screens on.
Usually it's building something, like "I want to learn how to build a doll house" or "I want to learn how to make a shark sculpture
Channels are push content, this is more of a pull approach.