The Heisei era had Godzilla portrayed as often a rogue threat, King Ghiorah replacing him but representing a different kind of threat. American imperialism from the future if you will.
Finals Wars too portrayed Godzilla as a useful rogue, a living weapon that only followed his only alligance. Carrying a grudge against the humans notably. Monster X/Keizer Ghidorah kind of serving as his final boss. The alien trump car that the Gotengo crew realized had to be destroyed less the remaining world be put in jeopardy.
Then the Monsterverse introduced us to the concept of a natural balance Godzilla defends. With KOTM, Ghidorah kind of turns that on its head by beginning to destroy the Earth. We see then in GVK, Godzilla himself embracing his destructive capacity against humanity when they themselves agitate his sense of "alpha superiority" through the actions of APEX.
Finally in the Polygon continuity, we have Godzilla acting like an unstoppable exterminator. In the novelizations, going after other monsters one by one then driving humanity off Earth. He's ready to do it all again thousands of years later when humans return from space, it's like he has an instinct to destroy threats. Compared to previous Godzilla incarnations, G Earth is much more intolerant of potential threats like mankind. When Ghidorah is finally summoned by the Exif, well Godzilla's for the first time (briefly) facing off against an enemy that he can't pulverize into oblivion (at first).
With their shared status across several storylines compared, I'd say the better antagonist in each continuity would be:
For Showa: Godzilla
For Heisei: Godzilla
For Final Wars: close one, but Keizer Ghidorah.
For the Monsterverse: King Ghidorah
For the Polygon series: Godzilla.
In your opinion, who's the better antagonist for each series & overall?
