I've used Coats and Clark for years as well. For many years, it was all one could buy!
I use the cotton covered poly for regular sewing; the craft and machine type for my machine quilting; and the 100% cotton for hand quilting. There are also diff. thicknesses for top stitching and for buttons. You have to read the label !! Of course now JoAnn's only sells the 100% poly...it's okay too.
There is only one color that I had problems with... and it's the perfect blending color called FAWN - a dull purple-ish, gray-ish, beige-ish...Anyway... it always
frayed esp. when hand sewing my appliques. DARN!!! I loved that color!!!!