I think the 747 was the most meaningful, and it was also the biggest gamble for boeing. Look at what the 747 means today... It is still a huge player across the world, it is still the biggest airplane flying, and it is the most widely known airplane in the sky. Even when the A380 flies, there will probably be several people who will see them and think that they are a 747. "look, it's a 2 story, it must be a 747"