In an all time great sense, he's arguably greater than anyone this generation based on his weight class jumps and accomplishments. Overall, he's easily top 20.
One of the greatest of the last 20 or so years - top 3 at least in that period. He's behind Mayweather.
He wasn't "the man" in many of those higher weight classes and a few too many losses in his career against fighters that weren't "the cream of the crop" At best, he's #3 in this generation - some could argue for Calzaghe or even Hopkins being considered ahead of him.
That fact that you consider either of those guys over him or have him at best #3 shows that you don't know sh*t about boxing. Look back in 10 years and you will realize how amazing Pacquaio was. He's done things that we may never see again.
I hate this generations dumb undefeated fighter mentality. It hurts Pacquiao's ATG standing. No other generation cared this much about not losing fights.
Calzaghe never lost, beat some highly rated fighters where he was the underdog. Hopkins beat some of the best as the underdog. Pacquaio arguably was underdog in one of his top fights and lost it. I still have Pacquaio at #3 - because wrongly or rightly we reward people who jump weight classes more than people who own a weight class for a number of years. But you can make arguments that his best wins came against shop worn fighters.
A little different when you fought every couple of weeks to a month, while injured versus today. Losses today do matter, especially when you consider that he has had some pretty fortunate gifts protecting him further. Would you still argue his ATG standing if the Marquez fights had been scored correctly at 3-0-1 to Marquez? He's great, an ATG, probably just outside Top 25 for me but people have gone overboard for years about him just because he has a pretty style.
Going back THAT far to make a point shows me something about you. Fanboy. Can't be bothered. Barrera = only favorite because he handled Hamed. Nothing more, nothing less. When Pacquaio exploded, i.e post the Morales 2 fight, he lost the only fight he was an underdog in ( Mayweather ) and got beaten several times by Marquez despite being overdog. He was robbed against Bradley so I don't count that. But the best boxers of this generation handled him, Morales even handled him in their first fight.
Again, that's only because people don't regard people highly enough for staying in a single division and clearing it several times over. It's why Klitschko is never spoken of, despite his decade of dominance, because he didn't jump multiple divisions, which for some reason people think is some amazing feat.