Hi Gabriel,
I am the product manager for Cloud Run, and worked on App Engine in the past.
As you noticed, the very first thing to take into consideration is that App Engine is a GA product, Cloud Run was just been announced and is in early Beta.
At a high level, choosing between App Engine and Cloud Run is mostly about the abstraction layer you want to use:
- Cloud Run only takes container images, while this gives you flexibility but this also requires you to work with containers.
- App Engine takes source code. The experience is tailored to the various supported languages, and when deployed, the language runtimes are automatically updated for you.
(- Cloud Functions takes function as source code and offers a quick development experience)
We are heavily investing into App Engine, for example, at Next 2019, we announced the availability of new second generation runtimes as well as VPC access. We are committing to support our App Engine customers for the many years to come.
Today, App Engine has a lot of features that Cloud Run does not have: VPC access, Cloud SQL connectivity, the ability to do traffic migration or to serve static files.
I hope this helps.
We will publish more guidance in our official documentation.
Thanks for your message.
Steren