Just out of interest, what were the main challenges you faced when using Celery?
Celery is a task queue. Pika could definitely be used to build a task queue (similarly to how Celery is built on top of Kombu), but I can't think of many good reasons why that would pay off. Unless your use case was not a task queue...
Flask application context problems, hiding exceptions within tasks, Json Serialisation sometimes does weird things and hard to configure (the default, pickle, seems to be warned against as a security vulnerability), weirdness with Gevent/Socket.io flask stuff, difficulty (impossibility??) to emit socket events from within a worker, finally the canvas stuff seems great on the surface but I found it mind blowingly difficult to debug weirdness with it.
My Pika/RabbitMQ stuff was much easier to build, unit test and debug (i.e. it actually works). There is every chance the I am just a bit retarded when it comes to using celery, but the fact I've built the Pika version maybe these were just real issues? Dunno, it might all work flawlessly for you in which case it's a great tool.
Celery is a task queue. Pika could definitely be used to build a task queue (similarly to how Celery is built on top of Kombu), but I can't think of many good reasons why that would pay off. Unless your use case was not a task queue...