Front or Back wall diffusers

I would start on front. If you are set up along the long dimension, then the rear wall will be less important. My rear wall is pretty far back and I have book shelves there. That has given the biggest gains. Then sidewalls. You can simulate with heavy blankets or carpets.

As a general rule I like absorption right behind the MLP on the back wall and diffusors to the L and R of the absorption. Try front wall first.

It is recommended that the wall behind the speakers be reflective in nature, so that the sound develops properly. On the contrary, the wall located behind the listening position should be absorptive, so that the rear reflection of the sound does not interfere with the perception of the stereophonic image.

It is recommended that the wall behind the speakers be reflective in nature, so that the sound develops properly. On the contrary, the wall located behind the listening position should be absorptive, so that the rear reflection of the sound does not interfere with the perception of the stereophonic image.

Weird how you seem to answer your own question.

This is my point of view and it makes sense, but other people think differently and have diffusers on the rear wall. I would like a greater consensus and be sure to get the best result.