Python + Django or PHP + Zend Framework
when building a web 2.0 application, which one is superior in terms of

1. performance
2. availability of features 
3. documentation
4. ease of use

Python + Django combination or PHP + Zend combination?

Also how easy it is to migrate one to another, so if I have written stuff for PHP + Zend combination how easy is it to move them to the Python + Django option?
Python + Django or PHP + Zend Framework
===

when building a web 2.0 application, which one is superior in terms of

1. performance
2. availability of features 
3. documentation
4. ease of use

Python + Django combination or PHP + Zend combination?

Also how easy it is to migrate one to another, so if I have written stuff for PHP + Zend combination how easy is it to move them to the Python + Django option?