I like metrosene for garment sewing a lot, and I have used it for piecing. Yes, it is a polyester thread, but works well in my machine. Most of the time I use Superior SoFine 40 wt for piecing. It is also a poly but feels like cotton. I buy it in large cones in medium gray and medium tan and choose which one depending on whether I'm piecing mostly dark items or mostly light items. For quilting I have used about everything, but I probably use Aurifil the most. That is because my local shop carries it and it comes in lovely varigated colors that I like a lot. I have a Handiquilter Sweet 16, and I use the Superior SuperBob prowound bobbins for my quilting just about all the time. I generally choose a neutral color that matches the back.
Pam