Player's Handbook and which other book?

UPDATE: We've chosen Tasha's Cauldron of Everything for our additional book. The list of available options this provides is laid out in this post.

ORIGINAL POST: There are a lot of player character options that have been produced since the beginning of D&D5, scattered across several books: races, classes, sub-classes, spells. In this game, we will be using the Player's Handbook and ONE other book for our PC options.

Which book should we choose?

Here's a summary of some of the things (races, classes, and backgrounds) that some of the books provide:

The Sword Coast Adventurer's Guide is filled with backgrounds (though some would have to be adjusted for localization, as we are not playing in Faerun): City Watch, Clan Crafter, Cloistered Scholar, Courtier, Faction Agent, Far Traveler, Inheritor, Investigator, Knight of the Order, Mercenary Veteran, Tribe Member, Urban Bounty Hunter, Waterdhavian Noble

The Dungeon Master's Guide adds the Aasimar as a playable race.

The Mythic Odysseys of Theros adds some races and a background: Centaur, Leonin, Minotaur, Satyr, Triton, and Athlete.

The Guidmaster's Guide to Ravnica adds some races and backgrounds: Centaur, Goblin, Loxodon, Minotaur, Simic Hybrid, Vedalken, Azorius Functionary, Boros Legionnaire, Dimir Operative, Golgari Agent, Gruul Anarch, Izzet Engineer, Orzhov Representative, Rakdos Cultist, Selesnya Initiate, and Simic Scientist.

The Explorer's Guide to Wildemount adds some races and backgrounds: Aarakocra, Aasimar, Bugbear, Firbolg, Genasi, Goblin, Goliath, Hobgoblin, Kenku, Orc, Tabaxi, Tortle, Augen Trust, Cobalt Scholar, Grinner, Luxonborn, Myriad Operative, Revelry Pirate, Volstrucker Agent

Eberron: Rising from the Ashes adds some races, a background, and a class: Bugbear, Changeling, Goblin, Hobgoblin, Kalashtar, Orc, Shifter, Artificer, and House Agent.

Tasha' Cauldron of Everything adds the Artificer.

Mordenkainen's Tome of Foes adds the Gith.

Volo's Guide to Monsters adds races: Aasimar, Bugbear, Firbolg, Goblin, Goliath, Hobgoblin, Kenku, Kobold, Lizardfolk, Orc, Tabaxi, Triton, and Yuan-Ti Pureblood.

Are there other books we should consider, or spells that appear in a particular book that you feel should be mentioned?

I don't have the book, but are there campaign-specific races that are available from the Greenwold book? I know the new one that's on Kickstarter has the mousekin and some sort of bug race, but I wasn't sure if you're using that version or not (or if that one is even out). I wanted to know about this first before casting a vote on the book, though as I mentioned in the recruitment thread, Tasha's is a pretty good choice.

No, no Greenwold-specific player options are available at the outset.

I vote Tasha’s please.

Quick Q: Are the class optional rules presented in Tasha's on the board if that is the book we settle on?

If the group chooses Tasha's Cauldron of Everything, the additional class (Artificer), additional spells, and various additional subclass options outlined in Chapter 1 will be available, but not the other options. If a group patron develops, it will be in the campaign, not as part of character generation. You don't want to maintain ties with Mara!

Edit: To be explicit, if we choose Tasha's Cauldron of Everything, here are the optional rules that will and will NOT be available:

I must admit I’m having a hard time choosing a 2nd book without knowing what class I want to play, and so what everyone wants to play. I guess Tasha’s has the most subclass options in general, so that gets my vote.

By optional rules, I was thinking along the lines of things like a Monk's "Dedicated Weapon" or "Ki Fueled Attack," or a Rogue's "Steady Aim"... things like that. (They're all listed as optional rules.)

So with those on the table (as all are part of Chapter 1), I'll probably cast my vote for Tasha's because it provides the most options for the players.

To be different. I choose Volo's Guide to Monsters.

I might’ve missed this, but are feats (from PHB) allowed?

No, Feats are not one of the optional rules we'll be using.

GM. Any idea on when you're going to close up on second book? Seems player selection was timely.

Hmm... is multiclassing an option?

The following Dungeons & Dragons 5e optional rules will be used:
climb onto a bigger creature – DMG pg. 271
disarm – DMG pg. 271
overrun – DMG pg. 272
shove aside – DMG pg. 272
cleaving through creatures – DMG pg. 272
Level Advancement without XP - DMG pg. 261
Classes, subclasses, races, and spells from the second book we choose may be used.

Players may use the following optional rule when generating characters:
Starting wealth - PHB pg. 143

No other optional or variant rules from the fifth edition D&D PHB will be used.

So far we have two potential votes for Tasha's Cauldron of Everything, and one vote for Volo's Guide to Monsters. Any other candidates we should consider? I will open the candidates as a poll shortly, but I wanted to give the other players a chance to chime in on their preference.

Alright, if multiclassing isn't being used I think I'll cast my vote for Xanathar's. It has arguably the two best Warlock subclasses.

Still put my vote in fir Volo's for odder races.

It's looking likely to be Tasha's Cauldron. There's two players who haven't voted yet, but if they don't vote in the next four hours, I will declare the top vote recipient the winner and open up the character generation thread. If there's a tie at that time, I'll figure out a random tiebreaker.

What races/classes are you all thinking about choosing for your PCs?

I’m likely to do human or half elf. TBH I voted Tasha’s on basis of reserving right to use Custom Lineage if rolls warranted. Since that’s not an option, I’ve no preference really. All good.