We migrated from Amazon SQS + Shoryuken to Sidekiq in order to have at-most-once delivery out of the box and more flexibility.
The UI builtin Rails makes it smoother for development and QA. Through the sidekiq rails engine we can easily see & understand which job is/was/will be executed, and even get some stats for free. Compared to SQS, we lose in scalability (need to manage the underlying Redis instance) but this is not so critical right now for our business size and the PROs clearly outweigh the CONs. Plugins allow to easily add distributed CRON scheduled jobs in there for almost free, and this is a core feature for us, so we no longer need to maintain a "scheduler" instance and we make our CRON jobs more resilient. The Sidekiq UI can easily be tweaked and for instance we have added a column that translates the CRON syntax into a human readable string, so it's easy for our Q/A to check whether the job is scheduled appropriately.
We still use Amazon SQS for some other apps, but no longer for our main Rails app.
