How much do you stress about picking a thread to sew or quilt with? Do you preview what you are going to use?
If you click on the picture to blow it up, you will see the gold works the best for blending. This is a shirt for Q, and I was going to do the blue until I previewed it and have since decided on the red. When I first started sewing, I chose the closest blending color, but now I often choose a color to show off the topstitching. For piecing a quilt top, I don't really care what color I use as long as it doesn't call attention to itself and will often choose gray. For quilting the top, it depends on whether or not I want the quilting to disappear into the top to show off the quilt or to call attention to itself. Sometimes I will chose a color that pulls the whole quilt together if it needs that.