There are still lots of threads I haven't yet but want to try. A lot depends on the type of quilting I am doing and personal preferences. I have many colors of Permacore thread and love it when I want the thread to really show. However, if I only want the texture to show or if I am doing lots of backtracking as in feathers or doing SITD, I love using So Fine #50 on top and Bottom Line in the bobbin. Another wonderful thing about using Bottom Line on bottom is the amount of thread you can get on a bobbin. You can quilt so much longer before switching or refilling. I have also used So Fine top and bottom with great results. However, as I said, there are SO MANY MORE that I still want to try. Just try out different threads and you'll soon find your favorites, at least until you find new favorites!