I do not favor any kind of world government - with one exception.
If and when aliens of the extraterrestial kind show up, I may reconsider my view at that point.
However, I do favor national governments working toward keeping the planet safe. So I don't have a problem with a few space guns up there pointed outward to blast away an asteroid (or alien invaders).
But we don't need to surrender our national sovereignty to do that.
The one exception?
If I were made World Empress.
Trust me. If that were the case we'd be all one big happy planet.