Aeon Magazine calls itself “an online magazine about nature, culture and ideas.”
Los Angeles Review of Books is what its title suggests, a book review.
Longform compiles great, in-depth reads from various sources.
Longreads is a lot like Longform.
Nautilus says, “Each month we choose a single topic. And each Thursday we publish a new chapter on that topic online. Each issue combines the sciences, culture and philosophy into a single story told by the world’s leading thinkers and writers.”