From my subscriptions:

Prozd Plays Games is a great let's play style channel. He's a voice actor and pretty funny.

NileRed is a chemistry madman who does very interesting experiments.

Technology Connections does deep dives into all sorts of household technologies: dishwashers, heat pumps, electric cars. He also dabbles in film photography, pinball machines, and other stuff I'm definitely forgetting.

Practical Engineering is a very high quality educational channel on civil engineering. Lately he's even started going to work sites and filming projects as they go.

Folding ideas does very well researched video essays. His flat earth video a couple years ago really took off but basically everything he puts out is incredibly interesting.

Tom Stanton doesn't upload much but he does model airplane and custom ebike content mostly.

Jenny Nicholson uploads once or twice a year now with theme park and weird media video essays.