It's the reason we watch. It's the way money is generated. Some feuds were so great WWE and WCW were printing their own money because of it. Some were so great it created revolutionized an era. Some were just so well booked it made us believe it was real.
Gotta make a point to say that although the longevity of a feud makes it great, it doesn't necessarily make it one of the greatest. In some cases the fact that a storyline was used based on a past feuds doesn't mean that it should rank higher than well thought out feuds that changed wrestling and will go down in history for it's own reasons. So although longevity did play a role in some of my picks, it was not the deciding factor.
My choice for the greatest feud to never happen. Hulk Hogan vs. Ric Flair. Sure they had a feud storlyines here and there, but what would have been the ultimate dream match turned into the greatest feud to never happen. The WCW feuds did nothing for us, by that time each man was overshadowed by the new generation of stars.
Enjoy the list and I look forward to your feedback as I always do.