Be the Judge - which do you prefer? iOS, Symbian or Android?

iOS -  Apple mobile operating system for Apple phones
Symbian OS - Operating system for all Nokia phones
Android OS- The latest Operating system the more recent phones; Samsung, Techno, HTC etc.
Blackberry OS - Operating system for blackberry devices.
Windows Mobile OS - -Operating System for Windows phone.

We have used them, tweak them and even altered them at some point, so its over to you now guys. Which of the above mentioned mobile phone operating system  would you say is the best?