I'm not sure about the best team just now.
I don't like 4-3-1-2 as a general rule.
But broadly speaking Juve are missing a midfielder with energy and drive to give the balance that is needed with Marchisio and Khedira. Juve need to play Sturaro to give the energy to over the space, but that obviously comes at the cost of technique.
And if you don't have the energy or drive in midfield, you need the forwards to do more. Obviously Higuain and Dybala are good players, but they aren't the players to stretch a game and work a defence in the way that would help Juve's midfield just now. Mandzukic would try, but he isn't quick enough to really do it.
So those factors push me to feeling more has to come from Juve in wide areas. But only Alex Sandro can consistently give a lot from fullback.
So I don't think there is a good option for Juve without a new signing.
Best i could come up with just now would be an awkward lop-sided sort of shape:
Buffon
Lichtsteiner-Bonucci-???????-Sandro
Cuadrado-??????-Marchisio-Pjanic
Dybala
Higuain
Pjanic can drift towards trequartista as Alex Sandro pushes up that flank.