Aurifil is a great thread, it is only two ply. Viking recommended it for my Mega quilter. its cotton so it'll hold up better than polyester because it won't cut thru fabric since its cotton. I use many different threads for many different projects but when it comes to putting together quilts I only use Aurifil, mainly because I have less problems with the seems being the right size which if you are doing a small block with many seams it makes a big difference. I was surprised when my civil war teacher showed me the difference. I also use it in my embroidery machine and have no problems with it.