I have found in the past to only have hubs for a single category only and keep it there. This helps more with keywords and relevance of the subject matter that relates to your Hub. You may find that moving your hub to a new category may lose traffic and need time to adjust to the new fluctuations and it may never gain as much traffic.
This has been my experience, hope this helps.
K-J this answer is helpful, and has provided me some direction on finding permanent homes for a few of my questionable hubs. Thx.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.