I usually press the seam down and then to the side; not always to the dark side though. I give a lot of thought to how the seams will nest if possible.
It is personal preference but I think that pressing open is not a good plan for stitch-in-the-ditch quilting, because you would be quilting down a thread between the pieces.
I prefer pressing to the side and when too many seams match at the center, I press those in the "flower pattern" in the center to where the bunched seam in the center is opened like a petal.