Yes, I understand that it's your opinion and I respect that.
About Gattuso / De Rossi / Bagni:
I didn't have the chance to see Bagni directly, I only know about his reputation of hard style and tenacious player, but there plenty of players with the same reputation, e.g. Romeo Benetti or Giuseppe Furino. And Benetti is the one with the best global reputation, but I repeat, they're players that I don't know very well.
Between Gattuso and De Rossi I don't hesitate a second to choose Gattuso. De Rossi has better technical skills but the importance of Gattuso's tackles in every team he played was enormous. Moreover, Rome's fans accuse him to do mediocre performaces during 3/4 of the season to suddenly return to a very good level in the final part of the season, especially in the years with national teams tournaments. And with national team he's a better player than with Rome, he does his best. By contrast, Gattuso was a player who always performed at 110% of his possibilities, both at a World Cup final and in a Milan-Cesena of the national cup. De Rossi is not loved by all Rome's fans, despite having played all his career in the club (till now), Gattuso was adored by Milan's fans. He won plenty of accolades during his career and was the player who guaranteed tactical equilibre to a team that played with Pirlo, Seedorf, Rui Costa and later Kaká in the midfield. The only important trophy in De Rossi's career is the 2006 World Cup, during which he didn't played four matches out of seven due to a red card against United States. Ok, it's only my personal opinion, but I tried to argument it with some facts
About the center-backs:
Even if I really appreciate Vierchowod and I think that he's underrated from Italian football fans (I have the impression that he's more appreciated abroad than in Italy), I think that the 4th place of all time is a little bit exaggerated. Maradona famously stated about him that it was relatively easy to dribble him, but that he was enormously tenacious and continued to run after him over and over again; he also said: "Vierchowod has muscles even in the eyebrows" lol. But Italy has had better defenders and it's not Vierchowod's fault, but rather the Italian school that is really great for goalkeepers and defenders. I'd put above him Franco Baresi, Scirea, Paolo Maldini (a central defender during a part of his career), Nesta and Fabio Cannavaro with no doubts. And we're already at five. Other Italian defenders with a better reputation than him are Bergomi, Gentile and Costacurta, even if they are favorite from the fact to haved played in winning and famous teams.