Pathfinder 2E Which book should I pick up next?

[Libertad]

Sometime this month I'll finish reading the NPC Core, which will be the final of the Remasters for me. I've found the books quite enjoyable reads, but wish to delve more into the world of Golarion via the Lost Omens line. I already read the World Guide, but what book should I pick up afterwards? I'm considering either the Tian Xia World Guide or the Mwangi Expanse, and heard that the Travel Guide is a fluffy in-universe look at various "daily life" activities of Golarion's people. But I am open to hearing other recommendations.

I'm not looking for adventures or adventure paths at the moment.