Maybe that UNIX discussion would become less heated when we start to talk case sensitive and distinguish UNIX, Unix and unix(oid).
Here's my question: how can you tell the difference? All these various OSs have the same underlying philosophy, the same features, run the same software (at least with respect to open source code, which is most of what I use) -- if you don't call them Unix, just what do you call them? If you say you prefer Linux to Unix, just what is it about Linux that you prefer? It does have a different licensing scheme, and as you note, it was written independently from the original AT&T codebase; but these things have no impact on day-to-day usage...