The most valuable feature by far has been the virtualization capabilities of the operating system. I can run multiple guests on "small footprint" hosts using the latest in Intel & AMD technologies, and take advantage of newer storage technologies, such as NVMe, to build lightning-fast hosts the size of a toaster.

I've also been able to provide rock-solid backup solutions such as URBackup, for example, compiled from source, that sits on stable platforms. They simply run until I restart them. 

The solution is easy for me to use because the backend is derived from FreeBSD and this is something I have been using for over 20 years.