why prefer Ubuntu over windows

It truly depends on the kind of use, following points are my assessment after using both for almost everything mentioned below:

1. Development(Programming, Software/web development, ...) Ubuntu - the best windows-you will survive
2. Entertainment(Movies, Photos, Songs, ...)
   Ubuntu - Can do everything what windows can do
   Windows - very intuitive
3. Office work(Word, Excel, ...)
   Ubuntu - you can survive with Wine and MS Office but not the best experience
   Windows - the best
4. Gaming(CS, NFS, COD, ...)
   Ubuntu - nah!
   Windows - the best
5. Adobe creative suite(Photoshop, After effects, ...)
   Ubuntu - Photoshop CS4 using Wine, so consider it not there
   Windows - awesome support
6. Performance(RAM utilization, Core utilization, ...)
   Ubuntu - Better than windows
   Windows - okay
7. Productivity(Explorer, theme, applications, ...)
   Ubuntu (unity) - Really awesome
   Windows (7) - good
8. Security(Antivirus, firewall, ...)
   Ubuntu - awesome, no antivirus needed
   Windows - there is always one more virus
9. Learning curve
   Ubuntu - kind of steep learning curve
   Windows - easy
10. Support(updates, ...)