FreeBSD continues to impress me. As a one-time Windows-only user until the past 5 years or so, FreeBSD lured me into a higher realm of computing that various Linux distros never could. And, furthermore, it did what Linux itself could not: it brought me to terms with Linux in that I actually use it too. In truth, today, I use all three regularly and I am more skilled, knowledgable, and successful for it - and my career isn't even all that technical.