MM, MToF or VGtM for Roll20 Campaign?

[Xapi]

So, I have started DMing a Campaign in Roll20.

The campaign's arc is all my doing, although I am picking up an adventure or two as sidequests and stuff.

I started it all just using the "free" compendium stuff, but since we really hit it off and it was my birthday, I was gifted the PHB and XGtE by my sister (who plays in the campaign) and mom.

So far I have used kobolds, thugs, bandits, cultists and acolytes as foes, plus a couple of spiders and wolves encounters.

So now I am pondering adding a "foe" book to have some versatility when making encounters. The campaign is not monster focused, most adversaries will be humanoid, and although there's a "draconic" thing going on, there's very few actual dragons. Of course monsters will probably make up a good chunk of the "sidequest" material. Around level 5 or 6 I expect them to head for a mountain biome which will feature some giants. The PC's are now level 3, and I expect them to go to at most lvl 12 in the course of the campaign.

So the question is, which book will give me the most bang for my buck in this campaign? I fear MToF is mostly high level, but it's an assumption and nothing else, while it feels like much of the MM is in the SRD anyway, so my lean is towards VGtM, but I feel I might be really really wrong here, as I haven't actually read through any of the three books, and I am uncertain as to how much content from the MM is actually in the SRD, if any.

[1Pirate]

I think VGtM will serve you best. I wouldn't describe creatures in MToF as high-level exactly(though there certainly are quite a few-might be skewed because of all the demon-lord/Archdevil stat blocks) but rather more exotic.

Volo's will probably give you more variants on things you already use or creatures that could live in a similar setting to what you're using now.

[MaxWilson]

So the question is, which book will give me the most bang for my buck in this campaign? I fear MToF is mostly high level, but it's an assumption and nothing else, while it feels like much of the MM is in the SRD anyway, so my lean is towards VGtM, but I feel I might be really really wrong here, as I haven't actually read through any of the three books, and I am uncertain as to how much content from the MM is actually in the SRD, if any.

You're right about MToF, it shouldn't see much use in a low-level campaign. I'm not sure how much the SRD contains, although I believe it's missing iconic monsters like mind flayers and beholders, but in a low-level game you might not even miss them, so even though MM is a valid choice there's nothing wrong with picking Volo's. Volo's has some quite interesting orc variants and hobgoblin variants, plus fey and neogi. Go for it!

[Xapi]

Thank you both! I'll take any other comments, but it seems my initial thoughts were about right.

[Eriol]

I'd say that the Monster Manual is what you want. It just has both the greatest variety, and the greatest number of baseline monsters to play with. Volo's is a good "augmentation" to it, and includes lower-level stuff, but it feels incomplete without the MM. It's like getting an expansion to the game without having the base game.

So Volo's is great, but I'd still say the MM is the way to go.