Seriously? But, but... Hufflepuffs would suck at being Dark Lords. There are important traits that Slytherins have that Hufflepuffs just tend not to have.
It seems to me Hufflepuffs are most likely to turn Magical Britain into well-meant but ruthlessly-run authoritarian state, with disastrous consequences for all.
Slytherins would probably turn against each other before achieving anything if one of them wasn't so much more powerful than anyone else.
Update: This post has also been superseded - new comments belong in the latest thread.
The second thread has now also exceeded 500 comments, so after 42 chapters of MoR it's time for a new thread.
From the first thread: