Most of mine have already been mentioned, but here are a few I didn't see:

• Songs by Spencer A guy named Spencer makes songs. Relatively new channel, but the production quality is top notch. I think his day job is owner of a video production company.

• Cheap Audio Man Reviews relatively cheap audio gear. Cheap is a pretty wide range in the audio world.

• Awesome Open Source Talks about open source software. Usually runs through how to install and basic usage/features.

• Chris Titus Tech Tech channel. Mostly Windows and Linux.

• Techno Tim Mostly homelab related stuff

• 66Samus Drum stuff

• Nicole van der Hoeven Obsidian.md / Personal Knowledge Management

• Rachel Maksy Cosplay / crafty stuff

• How to ADHD ADHD stuff

• Coffeezilla Covers scams, grifters, etc.

• James Hoffmann All things coffee

• The Kiffness Makes songs out of random internet clips of animals. Or remixes other people singing. My kids love this channel.