Easily the stuff with Mean Gene visiting Flair's home and rising in his car etc. in the run up to Starrcade 93 with Vader. That match really packs an emotional punch for me, and I don't think it would have gotten there without that build. One of the few truly great things WCW pulled off from start to finish.
The other one is DiBiase vs Duggan from Mid South, but I want Will or Kris to tell it.