A near perfect cyberman story for me.

In my option, there's three core elements that make the cybermen great, and by extention are needed for a great cyberman story:
1. Conversion: The threat of conversion is extremely important. If you're not terrified of conversion, might as well be a robot.
2. Inevitability: The cybermen should be able to come from anywhere, a 'natural' next step in human evolution.
3. Unstoppable: The cybermen can be beaten, they can be defeated, but they can never be vanquished. Going back to point one, they should be almost a fact of the universe.

Supremacy of the Cybermen has all three of these in spades.

Conversion is a major factor in all four of the split stories we're presented with here: Nine watching Rose being converted and killing Jack, Ten having to fight to prevent the cybermen from seizing a cloning factory which would let them infinitely reproduce, Eleven getting pseudo-converted himself, and of course Twelve seeing Gallifrey having been converted.

Inevitability is less of a factor here, the cybermen already existing in all the timelines we see, but there's something to be said for their conversion of other species, the seed being planted that not only could humanity succumb to this, but as could the Silurians.

And of course, how Unstoppable they are.

Nine in an apocalyptic London as the Cybermen have taken over, Ten fighting for his life, siding with the sontarans, being forced into an actual war, and succumbing to his worse impulses, Eleven watching as the Cybermen have taken over from the dawn of life on earth, failing to prevent them from lauching out into the stars, and Twelve, at the head of it all, seeing how it was all done, watching the conquest of time from where it's begun.

The cybermen presented here truly are unstoppable, and I adore it.

Each Doctor's story takes a different route in showing the attempts to stop the cybermen, and each doctor but one fails. The scale of the story is magnificent, and I think the fact that the doctors never end up meeting adds a lot to that scale as well.

The only thing keeping me from rating this a 10/10 is the ending. Some interesting designs for a cyber controller and potential far future cybermen is unfortunately not enough to distract from the fact that the story concludes with a big old reset button. On the one hand it did kind of have to, with how large scale it is, but the fact there's no consequences for it whatsoever does leave you somewhat unsatisfied.

That said, every single moment before that point works.