most of the time I use aurifil thread for piecing- my machines all seem to like it which is a nice change- some of the other choices I've made have not been as good from one machine to another- I like the smooth, fine stitching I get from aurifil. I also use silk thread, some of the connecting threads thread- YLI threads, -- depends on the project, the color I need, what I have on hand, what kind of stitching i'm doing, what the fabrics are like...but aurifil is generally my first choice.