when you say the word "best" in a question, you're pretty much asking me to step in and provide a complicated answer, so here it is
. there really isn't a "best" formation. you've got to take into consideration what your teammates' strengths are, as well as the style of play you're trying to get out of them. factor those two together, and then add the style of your opponent(s), and you'll get the correct formation. and in each formation you've got sub formations. in the midfield, assuming you've got 4 players, i can think of 3 main ways of positioning your men. you can have the straight line across, with 2 wingers, and 2 cenral mids; the diamond, with 2 wingers, and and attacking mid and a defending mid; or the brasilian square style with 2 attacking, and 2 defending. and even those formations can be broken down. i know you were asking for opinions, and just one answer, but i have to elaborate on this to get my point across. here's my pros and cons of some common formations.
4-4-2 - good overall, but depends on the opponent. more and more teams are using different formations. it leaves a lot of room in the midfield, and still allows the defense to do its job. the only real problem i see is that pretty much any other formation, when well used, can beat it at the back, as the defense many times has gaps where the opposition's strikers are positioned.
3-5-2 - a good counter to the common 4-4-2. pretty much a good all around formation. it takes a lot of skill to pull this off successfully, but if you've got the personnel, it works wonders. the only real flaw is the 3 at the back. it leaves a ton of space to work with for the opponent, and you need good defending transitional midfielders to work it well.
4-3-3 - the 4-4-2's weird cousin formation. take one out of the midfield and put him up on striker, and you've got a deadly combo of counter attacking ability and defensive strength. the weakness is the lack of players in the midfield. the other team is likely to exploit this and get a ton of room to make plays. again, it depends on how you use it.
3-4-3 - the 3-5-2's close relative. it's a more attacking approach to the traditional 3-5-2. you need a ton of defensive skill to execute it, but it works wonders. the main weakness is the lack of defenders, again.
so that's pretty much it. i know ratherton made a great
post in this earlier, but i needed to get my thoughts in the mix.