What makes a good setting guide?

There are a lot of settings available for TTRPGs; I feel like I have a hard time pinning down what stands out as a good example of what a setting guide should look like. For example, I've had a longrunning soft spot for Ravenloft, but not the actual source material. I love the concept behind the setting, but the books themselves are kind of "meh." They're adequate, but I'm not impressed by them. Yes, I'm not forgetting that the guides from AD&D 2e (i.e. Realms of Terror) are older and don't reflect the changes in layout and design newer products and publishers have embraced.

So, I'm throwing this out to the GPers. What is a good setting guide? What is an example of a book with great content and design/layout that isn't overwhelming? This isn't asking what your favourite setting is, but what's a great setting supplement for a TTRPG?

It happens to be my favorite, but I think Eberron: Rising from the Last War is a good setting book. The introduction does a good job explaining what sets Eberron apart from an easy list of things to know to explaining how draconic prophesies work to explaining how it has lots of magic but how it is all low level magic.

It then explains the character options but also introduced another major part of the setting: the dragonmarked houses, essentially the top dogs of the business world with magic behind why.

It then goes into 2 major things I think every setting needs to have: cool places and inspiring factions of villains. It really gets into Khorvaire and very into a city called Sharn but then hints at lots of places without telling the DM they must be a certain way while hinting at natural conflicts.

I feel you could get a whirlwind of answers for this. I prefer minimalistic setting books. I don't need rules for the setting I need info on how to introduce this world to my players.

How could players interact with cities, pantheons, folk lore? How do I build around that? If my player has a build character concept, I want the info to "yes and..." their backstory.

I really enjoy the Humblewood setting books for this, fairly lean "rules" for how things are done but a plethora of info you could use to help root your players backstories into the world.

I hope there is a whirlwind! I was just mulling, "What makes a ttrpg book quality?" and started wondering how that would apply to settings.

Eberron: Rising from the Last War and Humblewood

That's a good start

Some of my favorite, and probably most useful, sourcebooks I've owned and used were definitely more heavy on presenting the world/setting in a way that emphasized 'living' in that world. ShadowRun and Old WoD have some great books that are 95% highlighting elements of the setting with just a smattering of rules to supplement the setting.
Great setting books, for me, are almost like a collection of short stories more than chapters & chapters of rules or a catalog of equipment.

For most games, I appreciate one-page primers. Lazy DM has a good template for these. Write seven truths about the world. I like to make three about the broad world, two about the local region, and two about the immediate area. Then when you tailor the character options, you've really painted a picture

I saw something on Facebook today that reminded me of this. The question was: I understand that the lore behind World of Darkness games is great, but what about the system? And that's an answer to the setting question really. People will wade through sewers to engage in games where the lore and setting resonate with them.

But what makes WoD (in this case) so compelling if the system is lacklustre?

I think it's the broad strokes. The lore tells you all of these broad details about the fictional history and the current state of world, but it doesn't prescribe the finer details. There's plenty of space for you to say things like, what if I played a character who was the mayor or X, or the CEO of Y, or a rogue demon hunter for the Church of England, or ...

That's much different than saying: here's a list of all the major NPCs and a map of every building in the setting. Or different than saying, "it's an urban fantasy world with l where many monster movie monsters secretly engaged in their own political struggles. Go nuts." There's space to do what you want, but tons of lore for you to wrap around your Chronicle as you need it..

I'm of a similar mind on this. The best setting books draw you in as both GM and player, making you want to start a game there and now.

My most recent setting book that I purchased was The Atlas of the Latter Earth for Worlds Without Number. While there's a starter setting in the rulebook, it didn't really grab me. Then Atlas came out and I really, really wanted to start a campaign there.

It has maps of each country and region (I love maps: gaming, fiction, real world). There's a history, not only of the world, but of each country/region. Info on the people and culture, geography, one paragraph details on the major cities. For the bigger players, there's demographics. But each entry has a section entitled "Adventuring in..." that offers the GM two to three paragraphs meant to inspire possible adventure ideas. And each entry runs 1-8 pages (mostly 1-2 pages) with this information.

The book has supplemental info on monsters, character classes, optional rules, and NPC tags. While they're a nice add, I would've been fine without their inclusion. It was the included lore, the starting details, with room to fill in the gaps that got me.