We have considered stuff like RabbitMQ. They would be excellent solutions too and we are working on a part of our architecture with MQTT/protobuf (more on that later, I'm sure). We went with SNS/SQS because we don't have to build a cluster with that. Building clusters is hard and Amazon takes care of that. Since we were already using a bunch of AWS products, this was a nice fit and we're quite happy with it.

Authentication is a good idea for an article too. Thanks :)