In Clarksonian vein, this is a look at what ships can be honestly said to be the most powerful ships in the world at a given time.
Three examples.
HMS Devastation was the most powerful ship in the world when launched, and for the next dozen years at least.
HMS Dreadnought was the most powerful ship in the world when launched, but quickly rendered obsolete.
And the USS Enterprise (CVN-65) was when built the world's only nuclear carrier and largest (super!)carrier, so was in fact the most powerful ship in the world.
Any others?