I had an attempt with all three platforms.
I really enjoyed working with Perfect and deployed a simple server side app to production. I used their Perfect Assistant (PA) Mac App to help me deploy the application to an AWS EC2 instance. I followed a Ray Wenderlich video tutorial and everything worked perfectly. (https://www.raywenderlich.com/3989-server-side-swift-with-perfect/lessons/1). Upon deploying updates to AWS using PA I encountered issues and had to talk to the team on slack to resolve some Swift Package Manager (SPM) versioning issues with regards to Perfect, PA updates and what versions of swift the PA Mac App was writing to compile the application using SPM via PA vs version Xcode and SPM were using. (The PA Mac App would attempt to create a SPM package using a user interface.) Docker some times had issues with the latest image vs the PA Mac App image complier.
After all the back and fourth I decided I didn’t have time to handle the AWS Dev Ops set up along with the Perfect Assistant issues. I wanted to build a server side swift project and deploy it easily, after all the coding was done. That is when I looked into Vapor and saw they offered Vapor Cloud (https://vapor.cloud). Don’t get me wrong I loved Perfect as a server side swift framework. It was simple to use very explicit in what was returned from responses and made a lot of sense as a iOS swift developer. This was back in late 2017 so things may have changed. It is a great framework and highly recommend checking it out.
Great that it works on IBM Cloud Platforms. Easy to understand. Had a big issue with the response times of IBM support (was almost a month and a half and the issue was not responded to), attempting to use Watson with some server side swift. Seemed ok. It was not better than Perfect though.
Vapor seems to handle issues straight out of the box. Error responses were handled amazingly, Codable was a game changer and there were sufficient docs and community support for many issues. I do recommend Vapor as the winner.
Again Perfect was used a while ago (a year and a bit ago, an eternity in tech), it was great but Vapor seemed ahead of the game.