If two fighters fight close to their primes, does the winner of that fight settle the argument as to who is the better boxer? Assuming similair physicalities, of course. If not, why not? And if it is not as clear cut for you, what about a fighter who loses three times to the the same man? Can the loser of this trilogy still be considered the "better" fighter or is that now unreasonable? Can you think of any examples where two fighters meet close to prime and the better fighter loses?
There is no known formula, if there was there would be no need for this Forum... An example of a better fighter losing to a lesser fighter a couple of times despite the losing fighter being better would Mosley/Forrest. All you can say is styles make a fight and Forrest beat Mosley twice as a pro, also as an amateur I believe, despite being the lesser fighter.
It depends. If two fighters fight each other three times near their respective primes and a particular fighter comes out victorious on all three occasions then it absolutely must be conceded that he is the better head to head fighter. However, their superiority or inferiority in relation to other fighters may give a different picture as to who is to be ranked higher. In this question "styles" has a very big statement to make. A rather famous example may be Willie Pep and Sandy Saddler. Though I know that many may disagree with this.