They're is also developement tool on linux. In my work (hardware developement), tools are often unix (linux) only compatible. But I change to linux before to work on hardware. Actually I begin with MSDOS then I do w3.1,w95,98,2000 (xp like not ME). One day, after listen several people said that they installed a linux. I said to my self, if they can, I can do it too. I search to dl mandrake/mandriva. I create a dual boot. Quickly I use only linux, I did not find any difference with window. French police said there is 2 difference between win and linux, the first is game, the second is the different picture for icons...
Around 6-8 month later I switch to Debian and never change, I fell in love
No here the reason why I stay on linux.
1/ gui as easy to use as window. Well I become old, so I never use aero, compiz and co. I found all those craps slow at best. We probably don't have the same level of comparison for easy.
2/ very big number of software that I can install easily, I don't need to dig into all the web... Except all MS only video games.
2/ I can adapt the OS to me rather than adapt me to the OS. Can write small script easily to extend it.
3/ virtual desktop -> better than drugs
4/ command line. Very handy and efficient.
5/ free. Why pay when you can have somethings LEGAL and free?
6/ free software. When I got an issue I can get the code of my software and fix it. I can follow all the issue on a bug tracker and receive an email notification when it is fixed. there are lots of manuals. I can learn from it. And I learned a lots of things.
7/ Last but not least, highly reparable system. I do too much things with my computer and I'm not careful. I screw up a lots of things on my linux (including the boot loader), I always find a way to repair it. Sometimes it takes years to find the solution to an issue. On windows, I always ended to reinstall from scratch.
8/ I nearly forgot no virus, and slow antivir
So to conclude, it suit my need. I have a full control of my OS and it is highly enjoyable. It is always painful to go back to window (xp never saw 7 yet in my life) for any reason.