I also follow the FBW A320 development updates (still have not installed this mod though) and a lot of the things they mention that they added to the FBW A320 are already implemented in the Aerofly FS 2 A320. For example the fly by wire protections, realistic autopilot, etc. So there are areas where the Aerofly FS A320 still exceeds the freeware FBW mod but both products are still being worked on so I wouldn't want to make any list of what features are better in this or that.
I also haven't tested the Fenix A320 simulation. It's difficult to compare an add-on that is the price of our entire simulator. Our A320 is just one of many great aircraft in Aerofly FS 2, though probably the most detailed. Obviously can't dedicate the same amount of development time for a single aircraft as add-on developers...
What I like about our A320 is that you don't need to start any third party software first, no external update software or tools to assign joysticks, it just works of the box like any other Aerofly aircraft.