This is an excellent question, and there is no 100 % right answer. For instance, I bought a 100% cotton fabric that met all the criteria for a good fabric = weight, hand, color through and through, etc. - except that when I started sewing it, my 1/4" seam frayed away. That really upset me, especially since I paid full price and the fabric was absolutely perfect for the quilt I was using it in.
In my earlier quilting days, I bought some beautiful, thin cottons for quilting because I didn't know what to look for in a fabric. The fabrics were good, but I believe they would qualify as summer shirting fabric, very light weight and easier to see through. Nonetheless, I made quilts from them and the fabrics in the quilts have stood up to 7 years of abuse by my grandsons. The binding is fraying, and there are a few rough spots in them, but the boys don't notice them at all.
connecting threads fabrics are generally good quality and also generally at a lower price. I've purchased from Marshalls dry goods, 1001 bolts and only one nut, fabric.com, etc. and been happy with what I bought.
I shop in the Walmart near me, too. If you are careful you can get some wonderful fabrics at a good price. However, I wouldn't buy from them on line because their fabric quality varies greatly and I can't check it!
Good luck in your search!