- FreeBSD. The most well known, for sure.
- OpenBSD is ideal for you tin foil hat folks.
- NetBSD runs on everything, supposedly.
- PC-BSD and GhostBSD are all focused on the desktop. User-friendliness is not typically something associated with BSDs, so this is saying something.
Typical use case scenarios include embedded applications (NAS, routers, etc.) and servers. They tend to be "stable to a fault" which is to say you might not have the latest features, but it works, consistently.
BSD v. Linux
There's some glaring differences, in terms of init, default filesystems, the lack of procfs (!), etc., but they're both UNIX-like operating systems (read: *nix). However, remember that "GNU's Not UNIX," which is to say that the GNU part of GNU/Linux was meant to be a replacement for the POSIX standards that BSD adheres to. Is that good or bad? Who knows. But there are a lot of opinions. Some reading material for you to decide for yourself:
- Matthew D. Fuller urges you to consider the philosophical differences.
- FreeBSD talks about licences and such, but they also provide a handy guide for Linux users.
- Get used to the console. This is the default UI for most BSDs.
- Note that things are not the same. This is an extensive listing of console commands that include both Linux and UNIX options. Bookmark that! BSD is mostly a different world, in a much more dramatic way than, say, Slackware and Ubuntu are. As aforementioned, OS X is a completely different ball of wax.
- Have some familiarity with compiling software. The knowledge will be useful when you run into problems.
- Don't be afraid to read the manual(s).
To make life easy, it's recommended to use ports, unless you like compiling things from source yourself. It's essentially a package management system that offers a lot of control and flexibility.
On FreeBSD, portmaster is your friend. Use it. You can run portmaster -n -r package to do a dry run and see what other depends would get. Then you can check /usr/ports/UPDATING to see if there are any gotchas.
- bsd.org is a great resource for the novice and expert alike and has no official affiliation with BSD.