Book Recommendation

[Chalkarts]

I am a PermaDM.
I wish I weren't but it's the only way I can keep a weekly group going.
My personal library currently contains, The Holy Trinity and Tales from the Yawning Portal.

I have recently acquired the funds to expand my collection by 1 book.

What would you suggest what the next 5e book in my library should be?

[Lunali]

Normally I would suggest Xanathar's guide for the character creation options, there are also things in there to help DMs, but not enough to really be worthwhile on their own. Since you're permanently DMing, I'd say Mordenkainen, Volo's or Acquisitions Inc instead, depending on what sorts of things tickle your fancy.

Mordenkainen has a lot about the various endless wars, devils vs demons, elves vs drow, dwarves vs druegar, gith vs gith.

Volo's has a lot more detailed stuff about a few iconic enemies beholders, hags, illithid, orcs, goblins, kobolds.

Acq inc has ideas for a different style of campaign if you/your players have interest in adventuring as a business.

Also of note would be the Ravnica and Eberron books if you're interested in those worlds. As for the adventure books, I wouldn't recommend them unless you're interested in running that particular adventure. You can find enough information about them that you can probably figure out whether it interests you or not.

[ad_hoc]

Curse of Strahd is a great adventure.

[Bjarkmundur]

My most important resource and enjoyable read, after the Monster Manual, has been Waterdeep: Dragon Heist. Most of the other books have been fine just referencing, but waterdeep is a book I love being able to actually flip the pages. Especially since it is a resource as a whole, rather than individual chapters and mechanics like most other source books. For example, you usually just use the PHB or MM for looking up a single page. Settings are something you kinda need to digest as a whole.

I haven't read Curse of Strahd, but I'm sure it works by the same principle; Settings and stories work better as books rather than the occasional ctrl+f.

Believe it or not, I also recommend buying other game systems. They often have unique and interesting mechanics that is just a blast to steal. I recently implemented "Wrath Dice" from the 40k "Wrath and Glory" RPG, and I'm so happy I stumbled upon it. There's one marvel RPG that has very interesting character goal mechanic and 4e also had some really cool content like Manual of the Planes.

[jdolch]

Curse of Strahd is a great adventure.

I second that with one Caveat: CoS is dark and brutal. Just know what you're getting into. If you are more of the light-hearted-fun kinda guy who likes to keep his PCs alive, CoS is not for you. That being said, if you are willing to really submerse yourself in the World of Borovia and you can pull off the spooky, surreal Atmosphere in play, CoS is a great investment.

I am of course assuming you have the necessary rule books for being a GM or at least access to them. Don't quote me on that, i am not a DM, but those should be PHB, DMG and maybe MM although you should have stats for all relevant Monsters in the other Books+Adventure. I think both SCAG and XGtE are not worth buying if you are stretched that thin. You can use the most prominent features without having to own the whole books. Cantrips, Origins etc.

[Kane0]

If tale from the yawning portal dod you well, there is saltmarsh.

Other than that, storm kings thunder i like, and theres the upcoming descent into avernus

[Keravath]

Two I would suggest looking at would be:

Xanathar's Guide to Everything if you don't have it.
Saltmarsh seems like a pretty good adventure book along the lines of Tales of the Yawning Portal but the adventures seem to be more linked together.

[Chalkarts]

Two I would suggest looking at would be:

Xanathar's Guide to Everything if you don't have it.
Saltmarsh seems like a pretty good adventure book along the lines of Tales of the Yawning Portal but the adventures seem to be more linked together.

Is saltmarsh a seafaring adventure?

[HappyDaze]

Is saltmarsh a seafaring adventure?

It's several adventures, three of which are tightly linked and the other half are loosely associated. A few of them are seafaring, but all the rest take place near the coast.