I share your affection for the Nicomachean Ethics and other works of Aristotle, but I would not go as far as calling him the greatest mind of all times. I think his modern popularity is largely due to what happened after his death - the fact that our Arab neighbors, especially Averroes, preserved his writings until the Europeans emerged from their caves - so to speak - in the 12th century. Then, one Thomas Aquinas reiterated it almost verbatim (Catholics did not recognize intellectual property rights) added a few innovations of his own to reconcile A's teachings with the dogma of the Catholic church, and voila! - a star was born.
That is not to say that A was not great - he was - but that there are many more great thinkers of whom we know much less. Greatness is not as much a function of a writer's intellect (albeit some "global test" must be met in this department) - but of institutional framing and marketing. In other words, there are many great minds, but many if not most of them remain relatively unknown or totally obscure. Only those few who become champions or effigies of powerful institutions rise to popular stardom. The same works for arts, music, and politics.
Wojtek