#2 Stone Cold and The Rock
You can't talk about the Attitude Era and not talk about two of the most amazing wrestlers that ruled the time. Stone Cold Steve Austin and The Rock had varied backgrounds because SCSA had worked with various promotions before entering WWE (then WWF) while The Rock stepped into wrestling after his NFL career didn't go as planned.
It may sound funny to some, but their feud started for the Intercontinental Championship in 1997. The feud catapulted in 1998 when Stone Cold won the WWE Heavyweight Championship for the first time, and the two had to collide between the ropes at WrestleMania 15 in 1999. The Rock joined Vince McMahon's Corporation stable and added more feud to the fire as Austin was already involved in a storyline with the chairman of the company.
The two faced off at WrestleMania 15, and Austin won the title from The Rock, which then resulted in two more WrestleMania matches between the two where they stole the show. The rivalry was on break when Austin had to leave the company for a year and take care of his neck injury.
The rivalry restarted after Austin returned, and it still amazes people with the way they presented the storyline to the fans.
Also read: 5 Steps to booking the WWE RAW Tag-Team Championships into relevance again