I'm a huge Nokia fan, never used other phones than Nokia, (once siemens for a 1 week or something). I liked Symbian, but its time has came to end.
I got big expectations about new meego and maybe I would use Windows phone 7 too because it's compatibility. But one thing is sure I didn't like new iPhone 4 system and cannot say why I didn't like ios, maybe because once I used Mac I realized that it has been made simple and working but it was too restricted of resources for me.
I have tried once android phone and can't say nothing about it at this point because it was so short time.
So I liked to know your opinions which one OS you got.