Calzaghe's resume is better, made a poll about this comparing the resume's of Calzaghe, Hamed, Hatton, and Froch.
Calzaghe's wins over Kessler and Hopkins (though it was controversial a little bit) make his the best. Hatton was 2nd in my opinion. His Tszyu win was a big big big win, but now some try to discredit that because it was Tszyu's last fight. But Tszyu was the best JWW in the world and was #3 P4P at the time, and Hatton had a lot of other solid wins over Top contenders as well. Froch was 3rd in my opinion. If he avenges his Kessler loss in cinvincing fashion, he'd be ahead of Hatton in my book. And Hamed had a lot of solid wins over Top contenders, but not a really huge or defining win.
Calzaghe's was clearly the best out of those 4, though I wouldn't call Joe an ATG. He's a HOF fighter, but his resume isn't ATG status.