Please see the most recent updates in the "Where did the .com name go?" thread. Posts number 16 and 17.
Exactly what you said TeaSea. "Is that based on a leap forward in technology, a significant impact upon aviation in general, a successful business platform, public perception?" All of this and more. There is no right answer. I was seeking opinions and have learned some things. For example, I think the Wright Flyer was significant not because it may or may not have been the first powered flight, but because it kicked off rapid development of aircraft in the early 20th century. Just my opinion.
Most in my list I find that "leap forward in technology and a significant impact upon aviation in general" go hand in hand.
Clearly so, and I find myself agreeing with your list on that basis. Absolutely on the Curtiss Golden Flyer, something Curtiss is not often given credit for due to his death (he really died to young to ensure his legacy) and the fight over the patents with the Wrights (for those not aware of the history, the Wrights worked for years suing anyone who attempted to make any type of control for an airplane claiming that their wing warping technology included ailerons).
Some of the aircraft on the list are pretty obscure and frankly, failures (The Comet set back jet air travel in the short term). Still, I would agree that they go on that list.
Interesting though in your list that only the DC-3 would be recognizable to the general public.
Excellent thread.