With any game, I try to find content from the best players and the best coaches – not just content that’s popular or entertaining.  Here are some good places I’ve found:

https://www.reddit.com/r/LoRCompetitive/ is a small community with guides and educational content.  This is the current tournament meta.  (as of sept 2020).

For the Ranked ladder: NicMakesPlays has a Twitch stream.  He’s reached #1 Masters and is often in the top 10.

Discord servers