Ranked in these QuestionsQuestion Ranking
Pro Open Source
RabbitMQ is licensed under the Mozilla Public License. Because it's such a core part of a system, it's better that it's open source to avoid expensive licensing or consulting fees.
Pro Uses a Broker Architecture
Messages in RabbitMQ are sent to a central broker before being passed to clients. This makes RabbitMQ a better choice if you are in need of more complicated methods of message passing such as routing and load balancing.
Pro Backed by Pivotal Software
Although RabbitMQ is open source, it is still backed by Pivotal Software, giving it a stronger financial and developer backing. It also means there's a company to go to if you need help scaling in the future.
Pro Written in Erlang
Erlang is a fast concurrent language designed for non-stop, real time, message passing applications, which makes it a great language for a message queue.