I use Connecting Threads 70wt poly on the cone. It's strong and makes a great bobbin thread when piecing. The 50 wt 3 ply is thicker then I like for piecing but it does fine with a larger needle size in my Bernina, Janome, Brother and Singer. I don't use the 50wt 3 ply in the bobbin. Aurifil is a brand name of Italian Egyptian Mako cotton, another brand of the same thread is Genziana. I buy it at Tristan Italian Threads. I have dozens of different brands of thread and each one is better at some sewing then others. My preference out of every thread I have ever used is silk thread. No lint, ever, and it's very strong and thin.