We have quite an extensive collection now, and I think what we look for has changed as it's grown. All of the above are important to some degree, but I think the main draw for us now is how innovative the toy is. What does it do? Is it different to what we already have? If so, how?
If it looks like it could be new and exciting then we then start weighing it up based on the above. But even then I couldn't pick just one.
They all get factored into whether it seems worth it or not.