pound for pound for pound list do cause some debate...That is because some people make list in different ways.....Some make it by putting a guy in every weight class and try to decide if he was that weight would he beat everyone in it....Some go by number of wins...others go by quality of opponents faced....
I base mine on a points system...1-10 ten being best of course....Then I rate every skill....EG. Offense, defense,heart,quality of opp,,ability to adapt to every type opponent,,jaw,,speed,,ring general ship,flaws,,overall skill..then I average the score and the fighter with the highest total wins...same for all time p4p list except when considering all time I only go by their prime...This is how I would rate a guy like Ray Robinson

Offense-10

Defense-9

Heart-10

Quality of opp-10

Ability to adapt-9

Jaw-9

speed-9

Ring Generalship-10

Flaws-9

Over all skill--9

Total==95

I use flaws because there is one thing everyfighter no matter how goodalways does that he shouldn't...Be it offense or defense...EG holds hands low at times,,pulls straight back,,lets himself get into situations he shouldn't..like slugfeast when he is a boxer,,allows himself to take unnecessary punishment...Then judge how often it has gotten him in trouble....Pretty much easiest way to do it