Its too hard to really say. The 90's were a HUGE revolution in terms of power/displacement ratios, with the intoduction of retardedly high revving small bore and high output bikes.
The 2000's introduced some cool stuff like EFI as a standard thing, radial brakes, stuff like that.
The 70's were just plain revolutionary because the Japs straight up redefined motorcycles as a whole, and set the bar with dependable 4 cylinder bikes with disc brakes standard, and very well engineered motors.
The 80's aside from introduction of fully faired purpose built sportbikes, really to me wasnt that much to write about.