My number one go-to choice for English Paper Piecing thread is Bottom Line thread by Superior Threads. This 60 wt. 2-ply polyester thread is fine and strong and gives me virtually invisible stitches in my English Paper Piecing projects. I also like to use this thread for all of my needle turn applique and sewing on binding as it glides through layers of fabric effortlessly. Another great quality is that it is Lint-free, and I find that it hardly ever frays when I am piecing using paper templates.
Not just for hand sewing, Bottom Line makes a fantastic bobbin thread for any type of sewing. Its lightweight, blending colors are easily matched with any top thread.