No, I'm not talking about in terms of combined mass in the ring, I'm talking about in terms of publicity and importance to the boxing world. What fight gets that distinction?
I don't know **** about the publicity factor, but for the purists i can contribute here. The one we want to see at the moment is big, let's leave that at that. Frazier-Ali 1 was one of them, Duran-Leonard may be the ultimate example of when the two best fighters ever shared a ring, ie combined skill in a ring at any given time was at it's all time highest. Out of curiosity though, how big was Zarate-Zamora for publicity at the time? Also, Frank Erne and Joe Gans were on some collision course.
I've got to agree with McGrain - Louis-Schmeling in 1938 is number 1, Johnson-Jeffries is number 2. I'd put Frazier-Ali I at #3. After that I'm not so certain. Today I'll say Tunney-Dempsey II at #4, Ali-Foreman at #5, and Ali-Liston I at #6. Ali-Liston may seem like a strange pick, but it seems like people were really paying attention at the time, even though they thought Liston would destroy Clay. Ed Sullivan brought his show, and the Beatles, down to Miami the Sunday before the fight, for what that's worth. In the U.S., that type of promotional coverage is only reserved for the Super Bowl these days.
Wales finest v Phillipines finest the fight the World demanded, fought in New York, USA. Jimmy Wilde v Pancho Villa , Jimmy Wilde was given a massive sum for 1923 of £13,000 pounds sterling, to tempt him out of his two and a half year retirement to fight the young Phillipino sensation Pancho Villa in the US.
Now that the last century is solidly behind us, only one fight carries the acronym "FOTC," and it's not Louis-Schmeling II. During the build-up, it was simply called, "The Fight." Louis-Schmeling II was obviously huge, and the passing of Louis led off the nationally broadcast news reports primarily on the basis of it. (I believe that was the last time the death of a boxing champion led mainstream news coverage, something not likely to happen again until the passing of Ali.) Louis himself did not want to be addressed as champion until defeating Schmeling, and may have always privately considered this the true beginning of his landmark reign. After those bouts, it depends on whether you're referring to significance before and during, or after the fact. I'll toss out some other matches for consideration here. Tunney-Dempsey I & II Corbett-Sullivan Fitzsimmons-Corbett. This one was important enough for Enoch Rector to film on location, allowing everybody an opportunity to see the same competitive bout for the first time, not just read about it. Holmes-Ali. This may have actually been the biggest boxing event in world history, as it was broadcast live to the U.S.S.R. and People's Republic of China. Ali was far bigger than John Lennon ever imagined the Beatles to be, as Red China's state controlled media only acknowledged the existence of the Beatles for the first time when he was murdered (a couple months after Holmes-Ali). The Beatles (and rock music in general) were outlawed in the other Communist states. Ali is infinitely more transcendent. Duran-Leonard I. The biggest non heavyweight fight of my lifetime. Many believed that the larger and younger SRL was the P4P best in the world at the time. Duran leapfrogged the junior welterweight class to cement his all time P4P status. Dempsey-Willard, after the fact. At the end of the century, a prominent sports magazine (Sports Illustrated?) ran down their list of the most important of the last 100 years in sports. 1919 was at the top of that list, primarily on the basis of the sensational impact of Dempsey's dethroning of Willard. Johnson-Burns Ali-Foreman. The outcome of this one brought the HW Title out of mothballs. Muhammad was a great fighting champion, putting the title up five times in 1966, and twice before April of 1967. After dethroning Big George, he put it up for grabs four times in 1975, and four more times in 1976.