As of today (2019-03-20), both the current docker website, and the Ubuntu package have version
https://stackoverflow.com/questions/50427996/difference-installing-docker-from-ubuntu-repository-and-official-docker-reposito mentions that the Docker repo package might be newer, which is currently not the case.
Are there any reasons to use the Docker repository if you just want a stable install? Are there any differences between these? (Otherwise, it seems easier to avoid another repository, another trusted GPG key etc).