MetaShop: Instagram & Facebook

The good is designed specifically make social posting easier from shopify. Can create shoppable posts and schedule them. Supports Facebook, Instagram and several other platforms. The free plan is useful for getting started. Merchants praise its ease of setup, guides, and customer support. Some reviewers specifically report getting sales or increased activity after using it.
Important catch: not every feature is free. Auto Post Compaigns and things like video slideshow posts require an upgrade.
For PrintFlowStudio, I think we made the right choice, although, I would not pay for the upgrade yet.