Amazon ECS (Elastic Container Service) is the best choice for orchestrating containers as it allows you to easily run, stop, and manage containers on a cluster. It's well-integrated with AWS services, providing features such as elastic load balancing and auto-scaling that are essential for managing dynamic, microservice-based architectures. Amazon EC2 on its own does not provide orchestration features and would require additional management. Amazon EBS is a block storage service and is not used for container orchestration. Amazon RDS is a managed relational database service, and does not handle container orchestration.