I was struggling with the same question months ago and decided for Turbogears 2, and my reasoning was simple. "I'm new to python, I want to learn it not just for web-projects but as a substitute to php for scripting small helpers"
What I didn't like about Django, to me looks like a "close platform". ORM, Template system, sessions, etc they all are Django's
On the other hand, Turbogears 2 uses already known open platforms and just glued them, just like Appfuse does it for Java
With TurboGears 2 I learn SQLAlchemy that I can use later for small python scripts, or from the python shell to solve common tasks.
Main drawbacks are the lack of complete documentation and error messages.
Sometimes you have to search very deep to find simple solutions, the learning curve is steep, but it pays long term. The error messages where to me very confusing (coming from more than 10 years in Java development). I had lost many hours trying to find an "ascii encode error" when the real problem was a module not being imported.
That's my opinion, just remember I'm new to python and I could be wrong about many things stated here.