freebsd:
fast, very little overhead.
clean, clear structure, organized development
fast, yeah, I said it again. very efficient on slight hardware
easy, yep, freebsd is easy. read the handbook and be an expert.
small, build production servers that fit on compact flash cards.
I personally use ubuntu for my desktop as linux support for desktop style hardware is better, but I prefer freebsd for basic servers.
You can make comparisons to linux all day. They are both great. What sets freebsd apart is the developers and process. There is only 1 freebsd and because of that, it is clean and elegant in a way that linux can never be. Now, to be fair, I am of the opinion that there are only 1.5 linuxes out there which are debian and ubuntu so I am a bit skewed!