i try to buy the one that will stay in the quilt, fabrics at LQS are best line, I buy connecting threads online, I buy Joanns Better lines, rarely use walmart, they are 3rd or 4th grade or less weaving. Most online swaps wont take walmart, if you can see thru the fabric on your hand it is too thin and wont last thru a few washings. now if I want to practice something like I did recently I will use scraps or walmarts lower fabric lines. My Walmart is getting better fabrics in, but you still need to be careful. they need to be prewashed and pressed, LQS does not in my opinion