Some buttons for most common use cases that is what most of the current apps with Touch bar support do. For example, execute, new IntelliShell, change between views when exploring collections, edit selected document,...

Ideally the best option would be to offer several buttons and allow customized bar. You can check Chrome as reference.

I know my particular preferences but I don't know which actions are more common. Some tools collect that information from users and use that feedback to improve shortcuts, menus, etc.

Can you expand upon this? What functionalities do you think would work well in the touch bar?