Simplest Dutch System?

For someone who wants to learn the Dutch, which system is simplest to understand and wield - the Classical, Leningrad, or Stonewall?

Dutch defense.(only one I know)

The first opening I ever learned to play was the Stonewall Attack (for white) and Defense (for black). It's not a system, but an opening. I think that the difference is that there are simple plans and is good for a more positional\closed style of play, but you have to choose the moves considering what your opponent is doing, rather than just play the same stuff against everything. Although in higher ratings is kind too passive to play white, is a very good opening to start with.
Here's a crazy game of Magnus mixing trompowsky with stonewall.

The Dutch is a good opening but it‘s really hard to enter it properly. It is especially strong if White has committed himself to d4 which weakens e4. The question remains how to deal with move order issues like Nf3 and c4.

the Stonewall would be the simplest because the pawn structure is already fixed, so the themes and manoeuvers remain the same for the most part.