Amazon S3 is the best choice for this scenario because it offers virtually unlimited scalability for object storage, which is suitable for static content. It also provides high durability and low latency access, especially when combined with Amazon CloudFront for content delivery. Furthermore, S3 can handle rapid growth in access requests without the need for manual intervention to scale its infrastructure.

Amazon EFS would not be the best choice because, while it's scalable, it's designed for file storage and is more suitable for use cases that require a shared file system. Amazon EBS provides block-level storage and is not designed to serve static content to users over the internet. Amazon RDS provides relational database services, which is not an appropriate solution for serving static content.