One of the main factors in choosing Arsenal's best formation is who would be the main playmaker? Because if it was Nasri it wouldn't be about the killer passes, but if it was Fabregas or Ramsey it would be. So this is something Arsene needs to think about for the coming season.
AC Milan's 4-1-2-3
This formation is one of the most attacking formations I've seen used for a long time, and with the amount of attacking players we have it could work very well.
We could have Alex Song being a proper out and out anchorman hardly ever going forward, and then have maybe Ramsey and Wilshere in front of him as the main two creative midfielders with the usual Arsenal front three.
The only thing is with so many players forward, it will leave us exposed at the back, and with our defence at the moment, that's not the best thing to do, and also with Arsene wanting our defence to play such a high line we could be exposed to counter attacks more than ever.
And the formation would also require Robin van Persie to be the lone striker, when he would be better off as a second striker.
This formation is one that truly dominates the midfield, and allows the team to keep a lot of possession. So it would suit the Arsenal style of play.
You'd have the main centre midfielder (usually the more defensive one) in Alex Song.
Then you have your left and right midfielders in Gervinho, Arshavin, Walcott, Miyaichi, etc. They would be required to track back a lot, and support the defence just as much as the attack.
Then with two attacking midfielders, this could work well with Arsenal as they could possibly use Nasri and Fabregas (if they're still Arsenal players come August 13th) in these roles and combine the dribbling drives towards goal of Nasri, and the defence splitting passes of Fabregas.
And then in front of them, the only forward in the team, Robin van Persie. Once again he wouldn't be being used in his best position, but with the most three attacking players being Nasri, Fabregas and van Persie, it'd cause defences one hell of a problem.
The Christmas Tree 4-3-2-1
This formation was most notably used when Carlo Ancelotti was in charge of Milan and when Glenn Hoddle was England manager.
Wing backs would be used a lot due to the lack of wide players in this formation.
Then three centre midfielders, usually with one anchorman, and two box to box midfielders.
Then two players in second striker roles, so van Persie could be utilised very well, alongside either Arshavin or Nasri who could be used in their best position of just behind the striker.
Then the main man up front, who usually tends to be a proper target man with the second strikers the more skillful and creative players.
The formation would suit Arsenal's style of play, due to the three centre midfielders dominating possession along with the two second strikers who wouldn't be playing too far in front.
The diamond midfield 4-1-2-1-2
Used a lot by Chelsea in recent times, this formation involves there being one main attacking midfielder, with supporting wide midfielders, and then one anchorman who feeds the wide players and the attacking midfielder.
Then two strikers, usually with two strikers you could allow one to drop deeper and play the second striker which would suit Robin van Persie, but the attacking midfielder tends to play so high up he would essentially be the second striker as well. And therefore, van Persie would find space limited, but it would give him freedom to roam anywhere along the front.
Overall this formation wouldn't work for Arsenal because they simply have so many creative players and with just one main creative midfielder, a lot of the players would be wasted.