Science Fiction

Leviathan Wakes by James S. A. Corey

This one being missing is what stood out to me. I'm admittedly a bit of a fanboy of the series (and the TV adaptation) but it certainly feels like it deserves a spot to me. Like you said, it's good, accessible and fun, but I also think it handles geopolitics (well, solar system politics) in a fantastic and believable way.

I think the series understands human nature on a fundamental level. A lot of sci-fi is great at exploring high-concept ideas but it often tends to falter when it comes down to the personal, more human, individual level, I find. The Expanse series feels like its high-concept, sociological ideas are an extension of the individuals, which really helps to sell the world, I think. It also means the "villains" and the "evil factions" tend to have understandable, if not sometimes even relatable, motives.

It also just handles the science really well; the physics, especially, but also some biology, is integrated into the plot and world-building really nicely, but it never feels like you're reading a dense scientific journal filled with techno-babble. It gets across the concepts really well without getting bogged down with unnecessary details.