Yeah, I think Derek has a point -
"Most siginficant" means what? Advances in aerodynamic design? Breaking new ground in engineering processes? Record breaking? Created new materials manufacturing industries? Kill ratios? Production figures? Longevity of operational life? Miles flown? Visual aesthetics?
It's a bloody hard call, which ever way you look at it.
I have no idea where to begin because I have a great deal of knowledge about some of the aircraft listed, and virtually none about others.
Good luck y'all
LeeTree