earthquake
A friend from the time I lived in San Francisco was a committed collector. When the World Series was between the Giants and the A's he made a point of buying up the commemorative items at each game, both sides of the bay, whether he had tickets to the game or not. He was in the parking lot of Candlestick, next in line to buy a proof set of stamps from the USPS vendor booth, when the earthquake hit. When the shaking stopped he stepped up to the window and said "I'll take one of everything."
He has (had) a full set of all the USPS memorabilia postmarked at the only World Series game ever canceled due to an earthquake.
I was sitting in a hotel room with my parents in Memphis watching the beginning of the game (they still lived in the South Bay). Both my Dad and I reacted to the signal breaking off, assuming that some radical clowns had damaged the transmitter. Then we found out what really happened.
My sister and her family were still in the Bay Area. In fact their son was on a camping trip down near the epicenter, and they weren't heard from for many anxious hours. State Troopers and Park Rangers specifically went on a rescue mission to find this group of campers. They found them, perfectly safe and with water, latrines set up, food and a fire. The Troopers and Rangers paused for a minute and then asked "can we bring some folks here who have lost their homes?"
I second the motion for EARTHQUAKE as most exciting play.
Seriously, the "most exciting play" is the last one that made a difference in an important game.
It's like comparing "the immaculate reception" in Steelers history to "the catch" in 49ers history. It's context, not the nature of the play.