As far as AWA matches go, I can think of a couple that stand out in the spirit of this thread.
Nick Bockwinkel beating Verne Gagne for the AWA title in November of 1975 is one. For the AWA itself, it transitioned it's main star, Verne Gagne, into a part-time mode and marked an almost completely different philosophy in booking the Champion since he was a heel and was going to be in place for a long time. It was a huge and welcome switch from the lengthy reign of Verne, who at that point had exhausted all the angles and challengers that the fans were willing to see.
It also gave the world Nick Bockwinkel as a singles star and a much larger platform for Bobby Heenan to perform on.
The 1983 Super Sunday match between Bockwinkel and Hulk Hogan may also merit inclusion here. It is a devisive point in discussion of the career trajectory of both the AWA and of Hulk Hogan. Would he have propelled the AWA forward to new heights? Would Vince have grabbed him anyway? What was the actual planned finish vs. the result of the match? Was it the final catalyst in Vince deciding that Hogan was the one to carry his vision forward?
It's a serious watermark in AWA history, and given the prominence of the promotion it's value cannot be overlooked.
There may be more but those came to mind immediately.