Pacquiao has a greater legacy than Calzaghe.
Calzaghe did remain undefeated in his Career, but throughout in his career except the last 2 years, he has been fighting unknown fighters in his own home turf. He had all the advantage, the crowd, the judges, the arena and the referee. Emotionally and physically he is at a advantage against his opponent. Most of them are cherry picked to retain his title. Let me name a few, Calzaghe won the title against Chris Eubank, who is a boxer that also didn't fight outside of UK. It's like they are just manipulating the WBO title to remain in UK. Eubank won that WBO title in 1991 and he didn't beat any elite fighter, and Calzaghe stole it from him in 1997. Calzaghe, 9 years later finally got a tough opponent against Jeff Lacy, but he is just another overhyped fighter from the United States. He lost to Jermain Taylor who loss against Carl Froch and Pavlik. The Calzaghe fought Mikkel Kessler, he is the best fighter Calzaghe fought in his prime. But the 168-lb. is relatively weak compared to division beside it. The lastly, he fought two fighters who are 40-years old. Hopkins still managed to eek ought a close split decision loss, and Calzaghe never wanted to have a rematch. He then fought Roy Jones Jr. who is not capable to pull the trigger anymore. Calzaghe's legacy should not be based on those two wins at the end of his career. It should be in the 10 years he holds the Super Middleweight title facing Class-C and unknown fighters.
If I rank both Pacquiao and Calzaghe in the Top 100 All Time Great List, it will be.
TOP 25 - Manny Pacquiao
...
TOP 63 - Joe Calzaghe
--> Pacquiao fought Hall of Famers consistenly, and tought journeyman fighters. Hatton, De La Hoya, Marquez (2x), Morales (3x), Barrera (2x), Larios, Diaz, Ledwaba, Sasakul