I believe a top list to show a new fan should include wide variety of weight classes, and TKOs, KOs, subs, and quick finishes and grinding decisions, and also notable fights which are not necessarily spectacular (Lesnar vs Mir 1). The idea should be to show what to expect - if we show only 25 first-round KOs the reality will be very boring.
It also should be weighed heavily towards fighters who are active today - but still include some historic and pivotal ones. The fights should probably be accompanied by an explanation why they are on the list - whether the fighter is a legend (Wandy) or if the fight itself had an important impact in the sport (Sanchez vs Koscheck, Emelianenko vs Werdum). This way the newbie will understand there's more to the sport than guys beating the shit out of each other, and that there's a rich history despite its young age.
Could not agree more