Of the frameworks you talked about, Django has the most momentum and is likely to fit your framework ideals based on the Rails background. By this I mean that he has helpers that allow you to quickly generate your forms, although no forests. (Actually, the Django path is slightly better than the forests in Rails, because you can use all or just parts of it)
It has a good ORM with many helper methods and, one of the best features, it has a fully functional admin interface as soon as you define your models. You can start transferring data even during site development.
It also provides excellent user support, including permissions, access control, groups, user profiles.
It’s easy (and fun) to create your own mid-range and context-sensitive processors that allow you to abstract away from commonly used parts as plugins in the framework.
The only feature that Django has not mentioned above is NoSQL support. And this is only half true. If you want to use a non-relational database for some parts of your application, for example, to store sessions, you can. If you want to use it as your exclusive backend, you will lose some of Django's awesome features if you did not install Django with django-nonrel .
I used turbo gears, which are a combination of several other options that you talked about. There are great people in this community, but they are currently undergoing a major architecture upgrade and, frankly, they just don't pay as much attention to the developer as Django does.