Going back 20 years there is only one answer, Star Wars Episode 1. There can be no debate. It was a hugely anticipated movie and a brand new pinball platform full of potential.
What we got was a lousy movie full of uninspired special effects, a symmetrical play field with an uninspired rule set and the game that was directly responsible for the death of Williams pinball. That game was the start of the lowest point for the industry and nearly killed pinball.