I use Gutermann thread 90% of the time--I love it and my Juki seems to like it too, and I use it for piecing and quilting. I use their 100% natural cotton, 50 weight. I buy it in the large 3,281 yard cones. I shop around for the best price for the colors I use (usually neutrals, white and black) and find that I usually buy from one of three places: Quilting-Warehouse.com (about $14 per cone), or Overstock.com or Amazon.com (both of which will sell the large cones for $10-12 each if you watch the prices).