[Veen]

Three Quarks Daily often surfaces high-quality long form content from a broad ideological cross-section. As others have mentioned, Arts and Letters Daily is often interesting too.

https://3quarksdaily.com/

https://www.aldaily.com/

And, while I'm commenting, some of my favorite Substacks who tend to write long content are:

https://freddiedeboer.substack.com/

https://justinehsmith.substack.com/

https://astralcodexten.substack.com/

https://razib.substack.com/

https://www.theinsight.org/