My favorite OSs are in my signature.
I like Ubuntu, but I prefer them =)
OpenBSD for it's solidness and security, and Debian for it's compatibility.
I use OpenBSD for 90% of things and I use Debian for when I need to use a Linux program that simply wont run under the OpenBSD's compatibility layers. That's it really. *BSDs being rubbish as desktop OSs is really a myth.....