formation

433A works for me though I go with 424 for vsa.

I have seen people vouch for 4-1-2-1-2 narrow/wide and 4-2-3-1 formations as well

It depends on the players you have and your style.  I prefer 4-2-3-1 Narrow (2CDM+3CAM) for H2H. VSA, it's much of a muchness, whatever gets the highest OVR, lol.

Fr in vsa you get better chances in high ovr

The new tactics feature will be so difficult imagine if someone score 1 goal with starting formation 424 then after scoring he parks the bus 541

3-5-2 is the most meta formation..
2 cover cbs and one aggressive cb at the middle..
2 CDMs Lahm and Maklele preferably..
2 STs one has to be a trickster
Boom, you're 30stars in h2h(you need skills tho as well)

Yeah you need good agreesive defender as well

Every formation has strengths and weak points, even the ones considered as "bus parking" have "holes" in them.
 It really depends on how it actually gets deployed, we shall see, and this is when constructive feedback will be important.