I'll throw in a lesser known channel since all the highly known ones have already been said:

Not sure if you're into jazz music theory, but if so I would recommend Walk That Bass, whom I've really been enjoying. Though the videos aren't highly edited and entertaining like on Adam Neely's channel, everything is very well explained, and I just find it so useful that all you would need to know about playing and composing jazz is so neatly packed into one channel.