Unfortunately PowerShell doesn't have a conditional assignment statement like Perl ($var = (<condition>) ? 1 : 2;), but you can assign the output of an if statement to a variable:

$var = if (<condition>) { 1 } else { 2 }

Of course you could also do the "classic" approach and assign the variable directly in the respective branches:

if (<condition>) {
  $var = 1
} else {
  $var = 2
}

The second assignment doesn't supersede the first one, because only one of them is actually executed, depending on the result of the condition.

Another option (with a little more hack value) would be to calculate the values from the boolean result of the condition. Negate the boolean value, cast it to an int and add 1 to it:

$var = int) + 1

Is there a Scope Preference for Variables like there is for some other settings ($ErrorActionPreference, etc)?

No, scoping behavior is part of the language's core runtime semantics and is not configurable.

I'm working on a script that has a bunch of functions that call on information created in each other and I'm just looking to avoid writing $Script: or $Global: in front of each variable everytime

You don't need it everytime - you only need the scope modifier when you're writing to a parent scope.

Resolution of variables for reading will fall back through parent scopes and eventually the global scope, until a matching variable is found:

# variable defined at script scope, functions defined in here will fall back to resolving this when `$Config` is referenced
$Config = @{
  'setting' = 'initialValue'
}

function Update-Config {
  # Scope modifier is only necessary when "writing up" through the scope stack
  $script:Config = @{
    setting = 'updatedValue'
  }
}

function Do-Stuff {
  $setting = $Config['setting'] # no need to use script: here

  Write-Host "About to do something with '$setting'"
}

Do-Stuff
Update-Config
Do-Stuff

Executing the above in a script file will print:

About to do something with 'initialValue'
About to do something with 'updatedValue'

Note that for functions bound to a module, the script: scope is shared across the module - writing to $script:Variable in one module function will cause resolution of non-local $Variable to resolve correctly in any other function in the same module

For more information about scoped variable resolution, consult the about_Scopes help file

The PowerShell scopes article (about_Scopes) is nice, but too verbose, so this is quotation from my article:

In general, PowerShell scopes are like .NET scopes. They are:

• Global is public
• Script is internal
• Private is private
• Local is current stack level
• Numbered scopes are from 0..N where each step is up to stack level (and 0 is Local)

Here is simple example, which describes usage and effects of scopes:

$test = 'Global Scope'
Function Foo {
    $test = 'Function Scope'
    Write-Host $Global:test                                  # Global Scope
    Write-Host $Local:test                                   # Function Scope
    Write-Host $test                                         # Function Scope
    Write-Host (Get-Variable -Name test -ValueOnly -Scope 0) # Function Scope
    Write-Host (Get-Variable -Name test -ValueOnly -Scope 1) # Global Scope
}
Foo

As you can see, you can use $Global:test like syntax only with named scopes, $0:test will be always $null.

Here & is the Call operator.

The call operator executes in a child scope and the calling scope is the parent scope. Quoting from the documentation,

The functions or scripts you call may call other functions, creating a hierarchy of child scopes whose root scope is the global scope. Unless you explicitly make the items private, the items in the parent scope are available to the child scope.