Personally I'd go with Sir Lippi for the following reasons:
A- He was outstandingly sucessful with Juventus and won every possibly trophy to win.
B- He was successful with Italy and won the world cup
C- He was successful with three different Juventus teams, 1- the Viall/Paolo Sosai era, 2- The period were Zidane was there, 3- The period were Nedved was there (all had Del Piero

).
D- During the Lippi years Juventus did not have Big money as Inter, Milan, Man U, Chelsea (curently), Bayern ..etc. Never the less he led Juventus to be the strongest club in europe and maybe the world.
E- He has proven that what the Italian National Team needs is a good coach. They have the best players in the world. They've always had. But they rarely were maanged by a proper coach.
F- He is the best tactician in the world. Inside game manipulation was his thing. You all remembers changing Zambrotta from left to right or vice versa, shifting to Thuram to the centre back, shifting Del Piero from playing inside to playing wide to playing inside again.. etc or even with at the world cup for an example the germany game where he loosened up the midfield and strengthened the back and front because he read the game right and so no purpose for alot of midfielders since the game style has changed.
G- Knows his players and knows how to deal with them.
H- Led italy to the world cup in the worst year ever to strike the italian football where many ruled them out. He managed to unite the players under one roof.. his roof.
I- Because he has coached Juventus
