When creating a composer package, what "Package Type" should I choose
I found this as posting the question :
Composer Package Types
Out of the box, Composer supports four types:
library: This is the default. It will simply copy the files to /vendor.
project: This denotes a project rather than a library. For example application shells like the Symfony standard edition, CMSs like the SilverStripe installer or full fledged applications distributed as packages.
metapackage: An empty package that contains requirements and will trigger their installation, but contains no files and will not write anything to the filesystem.
composer-plugin: A package of type composer-plugin may provide an installer for other packages that have a custom type. Only use a custom type if you need custom logic during installation.
Package types are used for custom installation logic. If you have a package that needs some special logic, you can define a custom type. This could be a symfony-bundle, a wordpress-plugin or a typo3-cms-extension. These types will all be specific to certain projects, and they will need to provide an installer capable of installing packages of that type.