What criteria to consider the best boxer of all time?

Different people, different opinions. According to ESPN's 50 Greatest Boxers of All Time, there are four categories to consider: Achievements, In-ring Performance, Mainstream Appeal, and Dominance. Achievements depends on a fighter's success story. Most of the fighters won a fight despite of the odds and hindrances that affected their ability to fight. In-ring Performance is the most common factor that most people considered to become the best boxer of all time. Some fighters fight with a lightning speed like Ricky Hatton and Joe Calzaghe, others fight with rhythms and grooves like Roy Jones Jr and Floyd Mayweather Jr, and most of them fight with heavy punches like Mike Tyson and Jack Dempsey. It all depends on how they perform inside the ring that may nominate them to be the best of the best. Third criterion is the Mainstream Appeal, it all based on how popular they are on the overall boxing fans. The more people digging the fighter, the more exciting or great the fighter is considered. Lastly is the Dominance of the fighter. If the fighter can defend his title for a long period of time, definitely he can be the greatest fighter in his division. Again, those are the four criteria that determine the best boxer.

Those four criteria can be vague or loosely defined in some opinions. Like for example the dominance, a fighter can be a champion in his division but how about on other divisions? Will he survive fighting outside his division? We can't even give a fair match between a heavyweight and a lightweight fighters. So, how do we really consider the best boxer?

For my own opinion, to consider a fighter to be the best boxer, the boxer must have the ability to fight or defend himself against different fighters with different styles of fighting. The more styles he can do, the more chances of him to beat everyone and soar his name to the top of the list. Like for example, I can't consider Floyd Mayweather Jr as the greatest fighter of all time because he refused to fight a body puncher like Miguel Cotto. I don't say for sure that he could not be on the top of the list, he still have a chance to be on the top if other fighters have lesser styles than him. Another example is Manny Pacquiao, he is one of the most exciting fighter of all time, fastest fighter, and also a heavy puncher. But the thing is, most of his opponents are mexicans, and most mexicans have the same style of fighting. He should try African American style boxers like Roy Jones Jr and Mayweather Jr, or British style boxers like Hatton and Calzaghe, or others. Again the fighter must be "All Around Fighter" for him to capture the "Best Boxer of All Time" title.