But which was destroyed? The master or the apprentice?
Twenty years seems like a pretty good run. The Jedi all but wiped out. The Republic transformed into an Empire. The Sith ruled the galaxy. Seems pretty easy to say that Palpatine, Darth Sidious, was definitely the master and Darth Maul the apprentice, not even considering that Maul died before any of that was achieved.
Except it was Maul who was the apprentice. If not for a fluke defeat, which led to his premature death, Maul's vision would have stood for a thousand years, his leadership stronger than that of his apprentice Palpatine, a mere politician from Naboo, fluent in the arcane, filled with grandiose notions and fanciful ideas.
When Palpatine introduced himself to the Trade Federation, he did so while hiding Maul's existence. Either this is the mark of a master or the first telling detail of Maul's true role. The Sith had been driven into hiding, all but extinct, limited to a tradition of two rather than an entire and continually expanding brotherhood as in the Jedi Order. Consequently, it was Sith habit to remain in the shadows, which Palpatine was careful to do in his machinations concerning his home world. Maul humored his apprentice in these matters, remaining silent, remained focused, knowing these short-term goals were part of a chain of events that would bring glory back to the Sith. Palpatine's clairvoyance was always his dominant ability over Maul's own powers, something he had that his master didn't. But Maul understood Palpatine's visions better, which was always a disturbing matter between them. Without his guidance, Maul feared Palpatine would easily lead himself astray.
Which is, of course, exactly what happened.
Had he lived...things would have turned out differently. The Sith would not have been defeated, again, so easily, so quickly. Then again, maybe it was better that he died without knowing Palpatine's brief victory.
Perhaps, in his final moments, Darth Maul saw not the past but the future flash before his eyes. And that was his true agony.