NetBSD isn't an OS that will hold your hand during installation and set-up, but it's great for server applications and pretty good for desktop use. It also has a great source-based package manager, pkgsrc.
Tried NetBSD 7.1, but couldn't get Networking to work even though I tried to follow the directions. I do give credit for NetBSD's success with embedded devices and that it can run on a huge number of platforms. The main flaw is its very difficult to get it to work properly on the desktop, much more so than Slackware. With the exception of GNU/Hurd and Minix, NetBSD is the oldest FOSS operating system still maintained. A GhostBSD style variant of NetBSD would be welcome!