What's best between ember-addon and libraries

I would like to know, in a optimisation and reliable way:

would it be better to use ember-addon OR librairies and import it through ember-cli-build.js

For exemple, would it be better to install ember-cli-moment or npm install moment and import it in ember-cli-build.js like so app.import(node_modules/path_to_moment.js)

I know that the app.import may oversize the vendor.js size by copying all the content of the lib in vendor file. What about the ember-addonn way ? Is impacting the size of vendor.js too ?

I don't take in consideration the fact that you have some helper with the ember-addon way.

I'm only seeing the optimisations and the size of the final app.

What's your opinion ?
Thanks and have a good day !