Which flavor of BSD you chose should depend largely on what hardware the desktop uses. On an Intel- or AMD-based PC, FreeBSD is a stable and widely supported choice. For older hardware, or hardware that is not exactly mainstream, NetBSD might be a better solution. NetBSD is even more suitable for developing and deploying an application on one of the many embedded solutions, as you can probably use NetBSD on both platforms.
Mac OS X
Choosing a Desktop Solution
Choosing a Server Solution
If you need a Unix environment but also want access to commercial applications like Microsoft Office, or products from Adobe, Alias, and others, Mac OS X delivers the best of both worlds. The FreeBSD-like kernel provides a complete set of standard Unix utilities and libraries that enable you to use the BSD and OS X elements simultaneously.
For the record, OS X is my platform of choice. I develop Web applications using Perl, MySQL, and others while writing articles and books using Microsoft Word, all on a Power book G4 running OS X.
OpenBSD is the obvious choice on the server because of its very high security
principles. With such a safe environment it’s easy to deploy an OpenBSD-based server
without worrying too much that the system or network will be compromised. OpenBSD, in
particular, is ideal for use as a public-side server on the network and
for providing firewall and proxy services between the Internet and an internal network.
For a pure Web server, FreeBSD is also a good choice purely because of its stability
on key hardware platforms like x86. The quality of the disk drivers and networking
stack means exceptionally high levels of availability. It’s also possible to
make FreeBSD more secure by specifically disabling the services you don’t need to
If you prefer to work within the general security of the BSD platform, but with a
friendlier configuration and management environment, consider Mac OS X
Server. It provides all the benefits of the FreeBSD platform, with a friendlier front end.
OS X Server provides more extensive support for Apache; file sharing through NFS,
AppleTalk, and Samba; a built-in firewall and VPN; directory services through OpenLDAP; and
audio/video streaming through QuickTime. This functionality comes pre-configured
and ready to use.
All of this comes at a price. Unlike other offerings, OS X Server is a commercial
product. Although Darwin is free, the configuration and management tools built into OS X Server make it so nice to use compared to the other BSD
All in all, when evaluating a Unix-based OS other than Linux, all of the BSD variants are equally matched.