Re: Who uses FreeBSD in preference to Linux and why?
FreeBSD is better supported by binary drivers, but also has a consistent user space, great documentation, a decent disk back end, easy to understand firewall, and a reasonable init system. It's the most Linux like BSD there is, although less hardcore users may wish to use the desktop oriented PCBSD, which makes getting X up and running a little easier.
My favourite BSD is OpenBSD, a very carefully thought through system. NetBSD is a little more anarchic, and the most barebones of the BSDs. It's ability to easily cross compile is excellent, though.
It's also true that the packages/ports system is very similar on all the BSDs, and knowledge gained on one BSD is transferable to another. It is more than a little irritating that the BSDs have successfully used ifconfig for configuring every type of interface for years, whilst Linux distributions use a variety of different commands.
I'm fairly pragmatic about operating systems. My base operating system is Linux Salix, because I run everything on a Xen dom0, Slackware is too painful even for me (package dependencies, please!), and a NetBSD/Solaris dom0 is just not as functional, for graphics card hardware passthrough to VMs.
On top of Xen runs Windows (for app support, development, and some light gaming) and FreeBSD - because it's supported by NVidia, and the open source graphics drivers, whilst just about adequate, don't work well in VMs (a VM only looks like a real PC if you squint at it - typically it's a 440BX (pentium 2/3 era) or a Q45 (penryn era) chipset, with a more recent CPU than ever ran on those platforms, plus an odd BIOS, an ACPI table that looks like nothing else, and a few other oddities).
A couple of notes about BSDs : typically you can run with a generic kernel, and don't need to recompile. On OpenBSD you should definitely run with the stock kernel, it is unusual to try anything different, and error reports will be rejected. Also note that whilst it is generally quite safe to run OpenBSD -current snapshots as a day to day environment, this is not the case for NetBSD and FreeBSD - if you need them to work, use their stable environments.