I think there are plenty of channels that aren't just using "cheap stock photos and/or blender animations", and I can list some examples if you'd like. The first criterion is harder, though, because sci-com by its very nature isn't going to be original research, so channels in this category tend to be more creative or opinion-based (i.e. multi-hour video essays).

That said, if I'm trying to really get at the gist of what you're saying, I think you're looking for shows that have a lot of original work and high production value?

Some random examples I can think of (I'm sure there's plenty more):

• 3 Blue 1 Brown
• Captain Disillusion
• Gamers Nexus (specifically their investigations)
• Smarter Every Day
• Every Frame a Painting (inactive but with a huge catalogue)
• PBS Eons
• Technology Connections
• Montemayor
• Taylor Lorenz
• Climate Town
• Tantacrul

(this is excluding so many great video essayists and artists since the original comment seems not to be referring to those)