The very first... the Wright Flyer, and those aircraft of the next 5-10 years that developed the idea of flight.
The protagonists of the BoB; had that gone awry, things would have been very different around the world. So the Hurricane, Spitfire and the Bf109.
The WW2 heavy bombers. Lancaster, B-17, B-29 and to a lesser extent the B-24, Stirling etc.
The 707 for really bringing jet travel to the fore.
The 747 for making it a bit cheaper.
Not so much an aircraft, but an idea. ETOPS. Making the world smaller and even cheaper, with the A300,310,330, 757, 767, 777. I know there are others, but you don't really want to cross the Atlantic in a 737. Nor really a 757.
The 727, 737, A319/320/321, for making the short hauls accessible to the average man/woman/family.
Military jets - the Phantom, F16, MiG 21, MiG 29, thousands upon thousands of them made.
But the one that gets my vote is the CH-47. The Wokka is a beast of a machine. It perhaps doesn't really belong in this list, but it certainly changed my world. I loved flying in those things, and hooking under them. Spending a lazy afternoon on SPTA setting up for night flying, and then controlling them at night. Calling in a missing-man formation of them at a MACR's funeral. But above all, flying in them.
