My machine isn't picky about thread, so for piecing I will use whatever I have, be it cotton, poly or mix. I won't always use white or a neutral color either....have been known to use pink, blue, green, yellow as long as it doesn't show through. When I fmq, I like Connecting Threads essentials as it behaves well and looks good too. I refuse to spend $$$ on thread when the cheaper stuff works just as well.