I use neutral for light colors and gray for dark colors when piecing. For quilting it depends on the colors in the quilt.

I use off white or gray for piecing. I use ecru for quilting most of the time.
Sue

I love all the different color choices and use them all. When just piecing I use whatever I have more of or a neutral. When quilting anything goes! Top thread and bobbin matching.

for quilting i use many many colors- depends on the quilt- for piecing i'm not so...adventurous
i tend to use either white, black, gray or natural for piecing- sometimes though i will match the thread with the fabrics.

there are so many wonderful colorful threads on the market- it seems a shame to not use them- i love color!

I usually piece with a light/medium gray or tan, but I quilt with whatever looks good with the colors or tones in the quilt top. Sometimes I quilt with different colors in the top and in the bobbin, but it just depends on the look I'm after. When I'm auditioning threads for quilting, I am sometimes surprised at which thread color actually works the best.

I piece almost exclusively with a light grey. I don't have a TON of colors to quilt with, but I'm getting more adventurous. The quilt on the frame is a couple values of purple with a off white border. Only purples I had blended in to one or more of the fabrics. The owner and i agreed on a soft green. It shows up on all the fabrics but does not jumpe out and say I'm HERE!