Anyone who was around during the AE knows the answer isn't so simple. The NWO vs Sting is what created the era and Vince and Austin did not built things from the ground up. Austin too benefitted from an industry on fire. Vince stole WCW's fire by bringing in Tyson and Austin v McMahon did record business. By the time Rock came along WWF took WCW to the cleaners and won easily the war. The reason Rock is seen as the bigger star is because he lapped Austin 10x over outside the biz which matters. WWE got insanely popular because it went mainstream and Rock was the bigger mainstream star between the 2 and that was the case all the way back to late 99. The reason Austin is seen as the bigger star is the AE did revolve around him and he does have the strongest metrics behind him. You can argue it all day. Personally I remember seeing a lot more NWO shirts than Austin and never really saw a Rock shirt. Kids imitated Rock like crazy but they weren't wearing his shirts. But that's just my locality.