Best way to store modules?

Two ideas come to mind, but there are probably other options that might fit better.

It ultimately comes down to loading one module which has loaded the others:

 -- A ModuleScript, the parent of all of the other modules:
wait()
local t = {}
for _, child in pairs(script:GetChildren()) do
	t[child.Name] = require(child)
end
return t
-- (if you wanted to change naming convention automatically
-- you could do something like
-- t[child.Name:gsub("[Ll]ibrary", ""):lower()] = require(child)
-- etc. Otherwise, you could just name them how you want
-- them to be used (`utility` instead of `UtilityLibrary`)

-- A Script needing access to the modules
local M = require(game.ServerStorage:WaitForChild("Modules"))

M.utility.blah()

This is nice and clear and clean, but it's not great because of the M.. You could just use local utility = M.utility , etc, but then you'll have a statement per module, which is what you're trying to avoid.

Lua does have a 'solution' to this problem. Using getfenv and setfenv, you can dynamically create/change global variables.

I personally do not like allowing this much "magic". The main practical argument against it is that Script Analysis (and any other static-analysis tools you happen to have) will complain everywhere about where you use the modules. But I digress:

-- Loading module:
return function()
	wait()
	for _, child in pairs(script:GetChildren()) do
		local e = getfenv(0)
		e[child.Name] = require(child)
	end
end

Then you can simply use this as

-- A Script needing access to the modules
local M = require(game.ServerStorage:WaitForChild("Modules"))

utility.blah()

However, you'll get a pesky blue underline under utility since it isn't clear where it is defined.