Azure Service Bus, because it supports asynchronous messaging, high throughput, message ordering, dead-lettering, and seamless integration with other Azure services, making it ideal for complex distributed applications.

Azure Event Hubs, as it is optimized for high-throughput event ingestion and real-time analytics, but lacks native support for message ordering and dead-lettering required by the application.

Azure Storage Queues, offering a simple, cost-effective queue service with basic messaging capabilities, but it does not fully support message ordering or dead-lettering out of the box.

Azure Functions, which provides serverless execution for event-driven tasks but is not designed as a standalone messaging solution and lacks the necessary features like message ordering and dead-lettering.