I use high-quality 100% polyester, usually Gutermann, for sewing almost everything, hand and machine. Poly-wrapped cotton doesn't work well for me...it shreds and kinks in my machine due to differing fiber content.

What are you sewing with it? The all-poly also will help keep seams from puckering on cotton-blend fabrics after washing (especially places like top-stitching pleats on an x-kilt.)

If you are near a jo-Ann's, they have a 50% sale on Gutermann every few weeks or so, I stock up then on what I will need.

Moosedog