Play/Pause option for iTunes instead of global media for TouchBar
I am 5 reputation short of being able to make this a comment, but I think it's enough of a solution that I can post it as an answer.

I do not have better touch tool or a menu bar (I do have keyboard maestro and I know you could probably do it using that).

However, what you can do is either script the menu item or send a keystroke to iTunes using applescript. You can then run it out of automator (and assign it a keyboard shortcut) or BTT or somehow just activate it using your touch bar.

According to this reddit post (https://www.reddit.com/r/apple/comments/8okzvg/macos_mojava_supports_automator_workflows_on_the/) mojava will add automators to the touch bar.



Either way, here's a script: 

tell application "System Events"
    tell application "iTunes" to activate
    key code 49
    set visible of process "iTunes" to false
end tell


It's not perfect, but it gets the job done.