SPOILER ALERT
A giant genetically engineered telepathic octopus beast is teleported directly into times square and causes a psychic explosion killing millions?
Also here's my shameless additional tribute comic:
Skullbie
The squid ending was far superior because;
It sent a physic broadcast of what happened to people around the globe, ensuring that Ozymandias plan would outlive him. Also the squid spread was epic.
Another thing is the squid was an unknown entity and the people of earth could have no idea how strong it is-OR when it's coming back. They basically knew how strong Dr. Manhattan was and could probably tell if he was coming back or not.
It also ensured no one could ever trace this back to Ozymandias- and he was shown as much more conceited in his plan-making- Rorschach's journal more surprising.