Which AWS service will store this data MOST cost-effectively?

Explanations:

Amazon Aurora is a managed relational database service. It is designed for high availability and performance, which may lead to higher costs compared to other storage options.

Amazon Elastic File System (EFS) is a scalable file storage service for use with AWS Cloud services and on-premises resources. While it provides managed file storage, it is typically more expensive than S3 for storing large volumes of data.

Amazon Elastic Block Store (EBS) provides block storage for use with EC2 instances. It is optimized for performance but is not the most cost-effective option for storing large amounts of data.

Amazon S3 is an object storage service that offers a highly cost-effective way to store large amounts of data, including server logs, with flexible pricing tiers based on access frequency and redundancy requirements.