Maybe not the most powerful currently, due to how they were corrupted and pretty much killed off time and time again. Though now the dracthyr a direct product of Neltharion and likely many of them still aligning with the Black Dragonflight enter the picture. The Black Dragonflight now has access to the power of EVERY flight via Neltharion’s dracthyr. Also likely other new additions to the Black Dragonflight like the slitherdrakes, though they don’t seem to add much and are little more than animals. And also they now have a new aspect of their own.
They’re intended to be the protectors of the planet, so it’s either them or the blue dragon flight. Kind’ve hard to top magic. Magic lets people cheat.
Not that it matters, dragons suck and have failed in every conceivable way at their allotted tasks.
I’d argue, if we’re talking peak of their power, Bronze would have been the strongest. There’s a reason Aman’thul had to humble Nozdormu with a vision of his own death and instill such a strong moral mandate into them. Otherwise you get the Infinite, a flight who would erase you from history if they thought it would make a better world.
While dracthyr were created by Neltharion, I think it’s a bit of a stretch to say that more of them are allying with the black dragonflight. As opposed to the five flights in general. While we have seen a good amount of that in this patch, that seems to do more with the fact that this patch does focus mostly on the black flight.
As for the most powerful flight overall, I’d argue for bronze. The sheer potential to manipulate events for those who can walk through and manipulate time has allowed us to see the entire world vastly changed in various what-if scenarios. Ultimately, it seems like the bronze dragonflight’s only real limits are themselves, upholding their roles as keepers of time rather than manipulators.
However, their infinite dragonflight counterparts (which were, at some point, bronze dragons) have shown us plenty of ways as to how the course of the entire world could be altered by the changing of a few events.