The choice between using gcloud builds submit or docker build and docker push depends on your specific requirements and the context in which you are working.

Convenience: If you are already using Google Cloud Platform (GCP) and have the Google Cloud SDK (gcloud) installed, using gcloud builds submit can be more convenient. It integrates with other GCP services and provides a streamlined workflow for building and deploying applications on GCP.

Automation and CI/CD: gcloud builds submit is often used in automated build and deployment pipelines. It can be easily integrated into CI/CD systems such as Cloud Build, where you define build configurations in a YAML file and trigger builds automatically whenever changes occur in a repository. This approach simplifies the setup of automated workflows.

Flexibility and Portability: Using docker build and docker push commands directly provides more flexibility and portability. It allows you to work with container registries other than Google Container Registry (GCR) and is not tied to a specific cloud provider. This can be advantageous if you need to deploy your application to different environments or use container registries provided by other vendors.

In summary, both approaches have their advantages, and the choice depends on your specific needs and the context in which you are working. If you're working with Google Cloud Platform and prefer an integrated workflow, gcloud builds submit can be a good choice. If you require more flexibility and portability, or if you're already using Docker commands and established processes, using docker build and docker push directly may be the better option.