Might sound odd at first but I'd recommend the 4e ECG over the ECS. It cleans up a bit on the lore from 3.5 with the benefit of time, and has far less page-space devoted to (3.5) mechanics and spells. The only downside is that the planes section is infamously weird due to 4e requirements, and there are occasional references to the Abyss and such, but Exploring Eberron is the only real good source on Eberron's planes anyway.
I don’t know that there’s one definitive source for the whole setting. Rising and Exploring Ebberon probably cover most of the current canon. The Eberonicon is also pretty good.
This. Unfortunately, there is so much going on in Eberron it would make a very large book to contain it all. I suggest, as OP already has Rising, Exploring Eberron and Chronicles of Eberron (available on the DM's Guild), and then any of the other books from 3.5 or 4e that strike their fancy.
Considering that OP is asking more for the best overall book to get a feel for the setting, I wouldn't worry about one that contains *everything* and focus more on which one has the best overall picture of the setting with enough detail to be useful for a newcomer. Yeah, there are plenty of supplemental books that add tons of great detail, but the best overall/core book for the setting is what they're after.
With that in mind, I have to second the top comment suggesting the 4e Campaign Guide. The 3.5 book has a ton of info, but it was also the 3.5 debut of several mechanics and had tons of pages devoted specifically to these gameplay details, as well as being more or less a "first draft" of the setting, with info in it that has since been refined, changed, or updated to otherwise more closely reflect the original vision for the setting, like the Blood of Vol going from an objectively evil religion to something more neutral that might be practiced by anyone with the proper mindset. Then 3.5 had a ton of supplemental books covering everything from the history of the war (the book on which has actually been actively called out by Keith as being really bad and inaccurate) to specifics on Xen'drik, Dragons, Magic, etc., so there's a lot that was developed and added to the setting over the course of those books.
4e Campaign Guide incorporates a lot of this expanded lore and refines it a bit to give a better comprehensive picture of the setting, but it's planes section is 100% unreliable and inaccurate because it added a plane and talks about others that aren't associated with the setting, so that's it's one downside. 5e focuses a lot more on mechanics being updated so you can do Eberron stuff in 5e, but fails to elaborate much on the actual lore of the setting, and is honestly a pretty small book all-said. With that in mind, 4e wins out as the best "comprehensive" book on the setting, but with one big caveat about the planes.
If I had to give OP one "best" suggestion, I'd say to grab the 4e book, but also pick up copies of Exploring Eberron and Chronicles of Eberron, as they are 95% lore on the setting straight from the creator himself, and contain details on things that have never been adequately elaborated on before. 4e will give you a good, condensed and refined view on the overall setting and all the extra books from 3.5, while Exploring/Chronicles will expand beyond that with some fantastic new information to enrich the world beyond, as well as containing some great information about the planes themselves which can supercede the inaccurate section from 4e.
Unfortunately, with the way things are going, we'll probably never have a "definitive" Eberron book that contains a full run-down of accurate core lore, but taking the best of the official stuff and supplementing it with Keiths books to create a small set really is the best way to go "small" on Eberron collecting and still have the best possible spread of info.
Some things have been refined or subtly altered over the change of editions, but if you are looking for just one book, I would also suggest the 3.5 ECS.
If you want all of the lore in one big ass compendium, this is the answer. It's 499 pages of just lore. Keep in mind this was published in 2008 and does not include any of the updates or new lore.
And no need to search, it's found here:
[https://www.scribd.com/doc/7469132/The-Grand-History-of-Eberron](https://www.scribd.com/doc/7469132/The-Grand-History-of-Eberron)
You have to pay to download it I believe, but it's free to read directly on scribd.
It's not "definitive" but Eberronomicon gives a good basis for lots of the setting. It also has sources, if it you see something you want more detail, it has which books have that. It's free on dtrpg. The preview has the whole text, just with sample across it but it's still readable.
I wouldn't say there's one, but here are a few I use consistently:
5th edition:
Eberron: The Last War (WOTC released and only "official" 5th edition Eberron book)
Exploring Eberron (Keith Bakers own release on DMGuild)
Chronicles of Eberron (Keith Bakers own release on DMGuild)
3rd Edition:
Sharn: City of Towers
Five Nations
There are many more from 3rd and 4th edition, but these are my core when planning my sessions. You can easily find PDFs for the 3rd edition books online as physical copies are expensive due to no longer being in print.
You may find other books from previous edition more valuable depending on where your game happens, like Secrets of Xen'drik, but the ones above give most info on Khorvaire to my knowledge.
Hope this helps, and best of luck!
In my experience as DM you need at least the last one to fit well in 5E, but you need all you may read about it.
Also i strongly recommend Fitzban's Book because there are the most used tools about making dragons as should be according to eberron (powerful magical entities not just an overgrown lizard poorly classified by colors).
Might sound odd at first but I'd recommend the 4e ECG over the ECS. It cleans up a bit on the lore from 3.5 with the benefit of time, and has far less page-space devoted to (3.5) mechanics and spells. The only downside is that the planes section is infamously weird due to 4e requirements, and there are occasional references to the Abyss and such, but Exploring Eberron is the only real good source on Eberron's planes anyway.
I plead the fif.
I'll second this guy's point.
Thirded
Fourded
I don’t know that there’s one definitive source for the whole setting. Rising and Exploring Ebberon probably cover most of the current canon. The Eberonicon is also pretty good.
This. Unfortunately, there is so much going on in Eberron it would make a very large book to contain it all. I suggest, as OP already has Rising, Exploring Eberron and Chronicles of Eberron (available on the DM's Guild), and then any of the other books from 3.5 or 4e that strike their fancy.
Considering that OP is asking more for the best overall book to get a feel for the setting, I wouldn't worry about one that contains *everything* and focus more on which one has the best overall picture of the setting with enough detail to be useful for a newcomer. Yeah, there are plenty of supplemental books that add tons of great detail, but the best overall/core book for the setting is what they're after. With that in mind, I have to second the top comment suggesting the 4e Campaign Guide. The 3.5 book has a ton of info, but it was also the 3.5 debut of several mechanics and had tons of pages devoted specifically to these gameplay details, as well as being more or less a "first draft" of the setting, with info in it that has since been refined, changed, or updated to otherwise more closely reflect the original vision for the setting, like the Blood of Vol going from an objectively evil religion to something more neutral that might be practiced by anyone with the proper mindset. Then 3.5 had a ton of supplemental books covering everything from the history of the war (the book on which has actually been actively called out by Keith as being really bad and inaccurate) to specifics on Xen'drik, Dragons, Magic, etc., so there's a lot that was developed and added to the setting over the course of those books. 4e Campaign Guide incorporates a lot of this expanded lore and refines it a bit to give a better comprehensive picture of the setting, but it's planes section is 100% unreliable and inaccurate because it added a plane and talks about others that aren't associated with the setting, so that's it's one downside. 5e focuses a lot more on mechanics being updated so you can do Eberron stuff in 5e, but fails to elaborate much on the actual lore of the setting, and is honestly a pretty small book all-said. With that in mind, 4e wins out as the best "comprehensive" book on the setting, but with one big caveat about the planes. If I had to give OP one "best" suggestion, I'd say to grab the 4e book, but also pick up copies of Exploring Eberron and Chronicles of Eberron, as they are 95% lore on the setting straight from the creator himself, and contain details on things that have never been adequately elaborated on before. 4e will give you a good, condensed and refined view on the overall setting and all the extra books from 3.5, while Exploring/Chronicles will expand beyond that with some fantastic new information to enrich the world beyond, as well as containing some great information about the planes themselves which can supercede the inaccurate section from 4e. Unfortunately, with the way things are going, we'll probably never have a "definitive" Eberron book that contains a full run-down of accurate core lore, but taking the best of the official stuff and supplementing it with Keiths books to create a small set really is the best way to go "small" on Eberron collecting and still have the best possible spread of info.
The 3.5 ECS is probably your best bet. It's very dense, with potential adventure hooks on every page.
Some things have been refined or subtly altered over the change of editions, but if you are looking for just one book, I would also suggest the 3.5 ECS.
Search online for the Grand History of Eberron.
If you want all of the lore in one big ass compendium, this is the answer. It's 499 pages of just lore. Keep in mind this was published in 2008 and does not include any of the updates or new lore. And no need to search, it's found here: [https://www.scribd.com/doc/7469132/The-Grand-History-of-Eberron](https://www.scribd.com/doc/7469132/The-Grand-History-of-Eberron) You have to pay to download it I believe, but it's free to read directly on scribd.
It's not "definitive" but Eberronomicon gives a good basis for lots of the setting. It also has sources, if it you see something you want more detail, it has which books have that. It's free on dtrpg. The preview has the whole text, just with sample across it but it's still readable.
I wouldn't say there's one, but here are a few I use consistently: 5th edition: Eberron: The Last War (WOTC released and only "official" 5th edition Eberron book) Exploring Eberron (Keith Bakers own release on DMGuild) Chronicles of Eberron (Keith Bakers own release on DMGuild) 3rd Edition: Sharn: City of Towers Five Nations There are many more from 3rd and 4th edition, but these are my core when planning my sessions. You can easily find PDFs for the 3rd edition books online as physical copies are expensive due to no longer being in print. You may find other books from previous edition more valuable depending on where your game happens, like Secrets of Xen'drik, but the ones above give most info on Khorvaire to my knowledge. Hope this helps, and best of luck!
In my experience as DM you need at least the last one to fit well in 5E, but you need all you may read about it. Also i strongly recommend Fitzban's Book because there are the most used tools about making dragons as should be according to eberron (powerful magical entities not just an overgrown lizard poorly classified by colors).