I just bought my viking mega quilter this past year and was told the viking rep said the best thread to use that will cause the least breakage, etc is the aurofil. it comes in a variety of colors even though when I'm piecing I normally just use the neutral (suggested by all of the teachers that I've had) It is agreat thread; only two strands which gives me more of accurate seam allowance which is importand when you are doing small blocks. I just took a class with Normal Campbell and she also says use cotton, neutral color and we were doing 14 shades of blue, red and white. It looks great.