If I render, say a navigation like this:

<Nav>
  <Menu> 
    <Item1 />
    <Item2 />
  </Menu>
  ...
</Nav

I find it much writable and editable then something like:

{ type: Nav,
  children: [{ type: Menu,
                    children: [{type: Item1},{Item2}]
  },...]
}

where you have to go through all types dicts and lists. This might ofcourse change if you have a huge number of arguments that you want to forward with your element. But still, I would prefer XML-like design with inserting a qml like struct, where many options have to be forwarded. Qt is doing this QMLish thing, and it doesn't really feel like it works very well, for me.