For an always-on application running on Amazon EC2 that processes a growing backlog from an SQS queue for years, which EC2 purchasing option will deliver the greatest cost savings?

Savings Plans offer significant cost reductions (up to 72%) compared to On-Demand prices in exchange for a commitment to a consistent amount of compute usage (measured in $/hour) for a 1-year or 3-year term. For an always-on application with a predictable, long-term workload, this provides the greatest cost savings. Spot Instances are not suitable for always-on applications because they can be interrupted with a two-minute warning, making them ideal for fault-tolerant or flexible workloads, not critical, continuous processing. On-Demand Instances offer flexibility but are the most expensive option, providing no long-term cost savings. Dedicated Hosts are physical servers dedicated to your use, primarily for licensing requirements or specific compliance needs, and do not inherently provide cost savings over other options for general compute.