Twisted or Medusa or Zope

[mir nazim]

hi,
i m planning to start writing intranet applications and want ur real
cool advices for choosing the correct platform. the choice is between
the three:

1. Twisted
2. Medusa
3. Zope
(i do not know any of the three).

i want u people to help me choose the correct platform. 
my questions are:

1. which has the least learning curve.
2. which is best suited for the purpose for applications like workflow
automation, groupware, and other business related apps.

please also highlight the major diffrences between the three. 
also tell if there is a better alternative.

thanks in advance.