I always press to the dark so it doesnt show through to the light. I have always hand quilted and this is what I was taught. I'm beginning to learn how to machine quilt. I still press to the dark when possible for the same reason..

I agree that it's a personal preference, however I have a couple of reasons for pressing to the side, all of which have probably been mentioned above. First, the seam is definitely stronger. It's also much easier to get your seam intersections to come out perfectly when the seams are pressed to the side in opposite directions. Because of the little ridge created by pressing to the side, there is a definite point at which the seams lock or nest. If you pin on both sides, the intersection will be perfect. Finally, and I think most importantly, if you are stitching in the ditch when quilting, you absolutely need to press to the side, partly because then you have a definite "ditch" in which to stitch, but also because if you stitch in the ditch and the seams have been pressed open, you will basically be stitching on thread not fabric, which will eventually weaken the seam.

I have done it both ways. I guess it is up to you.

Personel preference but I select depending on project. Some blocks ie kaleidoscope see to go together better with open seams. Others really do need one way. Personally I mainly do one way as I was taught this way but also it is a stronger seam and the nest together easily . So my answer read the pattern you are doing and decide.

I have been quilting for 30 years and have always pressed my seams to the side, usually the darker fabric. Depending on what block you are making, you should always try to press to one side and the other piece should be ironed in the other direction so the seams nestle up and fit perfectly. Sometimes you have to lie out the block in rows to see exactly which way you want to iron so the seams nestle to each other.