[pgelephant]

Basically Postgres in Docker would be highly flexible in terms of what versions (major or minor), extensions, your own customisations for the configurations in pg.conf you want to go with.

You can upgrade/patch as soon as Postgres community makes these available. With RDS you have to wait and for Aurora surely significant waiting periods! e.g. Aurora Postgres is currently 2 major and 2 minor versions behind - meaning you would be missing the latest and greatest of Postgres!

I would suggest to use Postgres from community on EC2 or Containers or if you want Postgres as a service then use Postgres operator on EKS or any K8S distro available on AWS. You can easily go back and forth between this env and RDS or even any platform making your Postgres databases completely platform agnostic.