This guy may or may not be on your radar already. He's a professional composer with a great understanding of music theory and production and he does reaction videos mostly to modern alternative rock and metal music but branches out into other genres. He isn't creating content for music theory nerds because that already exists, but speaking in layman's terms about what makes particular songs stand out or work so well. As a huge Radiohead fan seeing him get blindsided and bamboozled by Paranoid Android is a lot of fun. I also just really like his wholesome, friendly vibe. He doesn't exude the hipster know-it-all ******bag vibe that too many music YTers have.

He's pumped out a TON of content since started doing reaction videos ~6 months ago. All his videos are great, but the Tool/A Perfect Circle/Puscifer content is my favorite.

Yeah, I'm not a fan of Tool but I noticed he's done a lot of those. It's cool that he takes suggestions from commenters. I also like that he doesn't really look into the bands/artists much before he does his reactions, so that they're really raw and unbiased. For example, I noticed that when he did Sigur Ros the other day he thought the vocalist was female (understandably).