I have found Walmart and JoAnns fabric to be of poor quality and not the best to be used in quilting. JoAnn's has much of their fabric made especially for them and with their label. They are much thinner and the colors and prints are not smooth and clear. They tend to be blurry. If you compare them to the fabrics in quilt shops, you will be able to tell the difference. I feel that if you are going to put so much time into making a quilt, you want it to be the best you can do. Yes, they are less expensive. But, this is a case where you get what you pay for.
I have 3 Walmart stores I can go to, all less then 10 miles away. There are 2 Joanns, both less then 10 miles away. I uaually don't consider them for fabrics, except for fleese. There are several LQS around within 20 miles , more or less. I make the rounds to the LQS for their sales. Most of the time I go to Fabric Depot, which is about 2-3 miles. I am very lucky to have such access.