Unix vs Linux, Well Unix is still around but it is mostly extienct. Unix was oringinal all text based while Linux was text and gui while Unix users could have a gui they preferd text. Now Solarus was the last version of Unix. You see Unix has been around for so long that new Unix versions eventual became new Operating systoms because they had nothing that made them Unix. BSD was once a version of Unix but over time changes to it was made and it became it'st own OS. Now as of 2012 Unix is officlely dead. Now its children BSD, Minux, Linux, Darwin, Windows are the new focus.
In 1998 an younge Bill Gates was at a school vist at Bell Labs (place where Linux was made) and he saw what the OS could do. That is when he came up with the idea of making a cheap home OS and they created a early prototype built on Unix. The Unix clone faild and Microsoft then created MS DOS and the first Windows OS simply called Windows.
Now lets move on, Mac was created the same way as Windows, but Mac chnaged things but was still consider a child of Unix. The code is changed but was based off Unix. This code would be changed and become a new OS called Darwin when OSX came out.
In 1992 a student neamed Linus created a terminal for a OS based on a child of Unix called Minux. Linux would make his os free to use and open soucre under GPL (diffrent story) In the years to pass a new company named Google would create a Linux distro called Android and latter Linux would have a baby called Chrome OS.
So Linux is the best choice.