Foley being thrown off the Hell in a Cell is the perfect #1 spot because up to that point no fan expected this to be physically possible without severe injury. The bottom line - no fan expected this to happen in reality.
Foley going through the cage was more spectacular and jarring. But HBK did a similar bump in the first. When Foley climbed the cell you knew he was taking a giant bump.
WCW being sold to WWF was shocking because, WWF won the Monday Night War and bought their main competition.