I guess it's by the License, software available and documentation. In my case (about 20 years ago) the documentation was what made me use BSD instead of Linux.

I guess it's by the License, software available and documentation. In my case (about 20 years ago) the documentation was what made me use BSD instead of Linux. Back in 1996 there was little (reliable) documentation about Linux kernel internals and boot process. For BSD (OpenBSD) it was the opposite: well documented and reliable.