I'm lucky that my machine is not finicky about thread. When I started quilting I used Star thread because that's the basic cotton thread that my LQS carries. I still use it for machine quilting, but for piecing I just love using 50 wt Aurifil. I buy that in white, ecru and lt. grey. It makes so much difference for me in my piecing accuracy. I also love how long my bobbin thread lasts.