Best orders for 4-4-2?

[dv8r]

I always played 3-1-4-2 flat with long passing

That's not considered "flat" though.

Usually when we say flat, it's based on the colour of the position.. So yours would effectively be a variation of 3-5-2, not a 3-5-2 flat but just 3-1-4-2. That's from my understanding anyway