I'll put my vote in for Ludwig & Ludwig's "Super-Ludwig" parallel snare system starting in 1924.
The "Camco" chain-drive BD pedal began as a upgrade done in drum shops. After the break-up of Camco, Hoshino produced the Camco chain-drive pedal in the early 80's.
Rogers Swiv-o-matic hardware, when introduced around 1960, all the other manufacturers had not progressed from their rail and spade hardware. It was so good, simple to adjust and sturdy, drummers would order un-drilled drums from another company and have the Rogers hardware installed at the shop.
I believe that Leedy introduced the swivel inserts/self-aligning rods for lugs and the "floating head" rims.