The only function I've added to my touch bar that wasn't previously available was Screenshot, because I do a lot of snapshotting and screen recording, and I'd rather hit that than the stupid Siri button.

I wish there was a way to add custom app-specific shortcuts to the touch bar (maybe there is? I'm not sure). I use Sketch a lot for designing, and I'd love to have access to my document colors and text styles in the touch bar, but no joy.