Unlike Linux which started as a copy of Unix (without the legal troubles), BSD was derived from the original AT&T Unix codebase. Under its permissive license it has been used as the basis for both proprietary (see SunOS/Solaris and OSX/Darwin) and free operating systems. Following the release of Net/2 which was released after rewriting or discarding all the AT&T code, a port to 80386 with 386BSD (which spawned NetBSD and FreeBSD) and the 2 year legal battle between Berkeley and AT&T (which settled out of court), 4.4BSD-lite(2) was released which was used either directly or indirectly by the BSD distributions that are around today. The main distributions are FreeBSD, OpenBSD, NetBSD, and Dragonfly BSD, but BSD has been used as the basis for or partially integrated into other systems. For example, Windows used the TCP/IP stack from BSD, Sony used BSD as the basis for thier PS3/PS4 operating system, and several Unix workstations in the 90s/00s used BSD as their basis. BSD is also an important part of companies like Netflix who use FreeBSD on their servers to deliver content over HTTPS. A critical difference between BSD and Linux is that the kernel and the base system are developed together as one piece rather than put together from separate projects. In addition, the use of the Ports system allows users to select between precomiled binaries or to build from the source code with any patches necessary applied automatically. You also get Jails which are similar to virtualization, but with the caveat that the kernel is shared with the base system. To be sure, you should be comfortable at the CLI if you want to build your system off of anything that isn't PC-BSD.
FreeBSD is the most popular distribution of BSD. Their focus is to be useful in a wide variety of applications from servers to desktops to anything you need. They do have some proprietary blobs for certain device drivers, but excluding that the system is free.
OpenBSD places its focus on security and correctness, while also staying as free as possible. The project has spawned things like OpenSSH, LibreSSL, and PF. It's been reported in the threads that OpenBSD will work for laptop use too (though as always do your own research).
NetBSD is focused on portability ("Of course it runs NetBSD"), both in the number of architectures that are supported and keeping the codebase easy to port to new systems. This is what you want if you want to take BSD into the embedded space.
Dragonfly BSD is an x86_64 only distribution that focuses on SMP and scalability. If you're running clusters of computers or like Amiga, you might want to look into this project.
PC-BSD aims to be a more user friendly distribution for traditional desktop use. It'll be a lot more familiar to people coming from Windows or OSX. You also get the a choice of different DEs on installation (though the default is KDE).