I have used alot of different threads now, but when I 1st started with my mid arm, I only used King Tut. I have a Gammill now and am much more equiped to tweek the tensions. I have branched out! My go to threads are Permacore (TONS of colors), Omni (same weight as Permacore but a nice sheen to it), Sew fine (for when I want to do a finer line, need to backtrack and don't want thread build up). I even just bought some SILK (but it was pricey!) I am going to use that on a quilt for my husband. That dear man has been waiting YEARS for me to finish his quilt! I buy most of my threads locally to me at Mulqueens or 35th Ave Sew and Vac. I got the silk online at Superior Threads.