I looked at all of those and they came nowhere near the convenience and software that Synology provides.
It's literally the "Why would you buy Dropbox when I can glue it together with rsync" level of ignorant comment, completely ignoring how behind most of those solutions like TrueNAS are in time cost.
I find that odd given that I literally run 3 Synologies and one TrueNAS - I've had the Synologies for over a decade and the TrueNAS for about three years now. They've all been great and do everything I want in a nas. Perhaps you are looking for more bells and whistles for something like DVR; I just do NFS + SMB and snapshots and remote backup.
It's literally the "Why would you buy Dropbox when I can glue it together with rsync" level of ignorant comment, completely ignoring how behind most of those solutions like TrueNAS are in time cost.