How good does RabbitMQ do in terms of availability nowadays? Because one thing a message queue should offer is high availability - otherwie it loses one of it's most compelling benefits.
Rabbit's quorum queues are an improvement on the extremely poor HA/clustering system they provided previously. Users can now choose between both.
Rabbit's defaults are still unfortunate, in my opinion: queues and messages are not disk-persisted by default, though this can easily be enabled. As a result, many folks run and benchmark a "high availability rabbit" only to discover that they're benchmarking distributed state stored in memory, not disk.
The one thing that made me pull back from RabbitMQ years ago was that using it between datacentres was a bad plan, because all the clustering was based on Erlang's underlying cluster implementation and the advice on that was not to use it between geographically distinct locations. I don't know if it's since improved or if that advice no longer holds, but working under an environment where we needed cross-DC redundancy made it impossible to select, for that reason.
