List of operating systems to their popularity wise

Hello friends hi. I just feel like an idiot for asking this type of question. But I want to know the list of the operating system to their popularity wise up to six so please let me know the operating system so that I can buy it. Thanking in advanced for helping me and me the suggestion and your precious time. Thank you.

Hey buddies hi the list of operating system is as follows:-
1. Windows (many versions and flavors like 7, Vista, XP, ME, 98, 95, etc.)
2. Apple operating System X (many versions too like Snow Leopard, etc.)
3. Apple iOS: 4.2.1
4. Linux (most number of flavors like Ubuntu, Mandriva, Lucid, etc.)
5. Disk Operating System.
6. Unix
I am not sure but I am just guessing it.

Hey dude I was just surfing on the internet and I saw the Question and the suggestion given to you the suggestions are quite systematic but I would like to recommend you that you should follow the list given below:
1) Windows
2) Operating system X
3) Linux
4) Solaris
5) Berkeley Software Distribution (BSD)
6) AmigaOS

Hey buddy from the discussion going on the topic I would like to recommend you that you should try the following list:

Here are some operating system name according to their popularity and year.

1. Windows xp (2002)
2. Windows 7 (2009)
3. Windows vista (2006)
4. Linux ubunto
5. Mac operating system (I don't know name of its version so please check it)
6. Windows server 2008 (for networking)
hope it work for you so please vote me to earn points.
Good luck!!!