Austin vs Mcmahon
Ric Flair vs. Dusty Rhodes
Rock vs Austin
WCW vs NWO
The Hardy Boyz, the Dudley Boyz, Edge and Christian
Shawn Micheals vs. Bret Hart-this rivalries from kayface to non kayface had so much impact on WWE. one of the thing got out of non-kayface rivalries is Shawn poney injuries give a chance Austin fued with Bret which put Austin on the map.
Stone Cold Steve Austin Vs The Rock take this one. The emotion, chemistry, excitement, shows by these 2 is just fascinating. Some that come close are Triple Vs The Rock, Austin Vs McMahon, Triple H Vs Austin, and some others.
Rock/Austin might be the hottest rivalry in wrestling but it's far from being the best wrestling feud. They were two of the biggest stars and that's what made their matches/encounters special. As a wrestling feud, Rock and Austin didn't do much.
Austin/McMahon might be the greatest rivalry because that was a bloody rivalry.
I think Austin/HHH and Rock/HHH are better rivalries than Austin/Rock because both involved a mega face and a mega heel whereas Austin/Rock was 2 mega faces. There was no heat. It was all about who was the best. With the other 2 it was deeply personal and that is the basis for a rivalry. Austin/McMahon too for obvious reasons.
DX vs Hart Foundation vs Austin. this was in 1997...DX had just formed (HBK/HHH/Chyna)....Bret Hart was a bad guy (Canadian hero tho), aligned with his brother and rest of Hart Foundation...Stone Cold was just being created, wrecking havoc trying to insert himself into the HBK/Bret feud...that whole year, started from May/June till Survivor Series i thought was awesome.
Of course, I loved the Austin/McMahon and Austin/Rock stuff too.