For as long as I am watching football, I can't remember a better and more complete defence than ours right now.
There were good defences in the past (Thuram-Canna-Zambrotta, Cafu-Nesta-Maldini) but all of them had week sports (zebina, Stam etc) and nowhere close to the depth we have.
The only downside is the age factor. But well, having an old defence and young attack is not so bad.