#1 Shawn Michaels and Bret "Hitman' Hart
Bret Hart vs Shawn Michaels is arguably the most popular personal feud in WWE/pro wrestling history. Both Superstars were great in the ring and they were top stars. Although they were presented on-screen as enemies, they legitimately didn't like each other in real life too.
HBK defeated The Hitman at WrestleMania XII to win the WWE Championship in a 60-minute Iron Man match. The plan was for the two Superstars to have a rematch at WrestleMania 13 where Hart would reclaim the title but Michaels suffered a knee injury forcing the plans to change.
In 1997, Bret Hart was about to leave WWE for WCW, but he still refused to drop the title to Michaels at Survivor Series in Canada. This led to the creation of the Montreal Screwjob. Thanks to Vince McMahon's orders, HBK won the title after locking Hart in the Sharpshooter, although the latter didn't submit.
The two Superstars shook hands and made up years later.