I can not attest to their Quilters Showcase line. But when I first started quilting I didn't know anything about using quilting fabric. I made two quilts from JoAnnes "Keepsake" cotton line. Going back 20 years this fabric was in the $3.99 price range while the name brand cottons were hovering around 6.99 to 7.99. Both quilts were hand quilted and they are used very little. One stays on my guest bed which gets very little use and has probably only been washed a half dozen times if that. The other, a lone star, I made for my bed and did use it for several years.
Both quilts have fabrics in them that have faded horribly and that is with little washing and very limited sunlight exposure. Not all of the fabrics faded, just some of them.
The one in my guest bedroom, where no animals are allowed and as I said before gets used very little has also had fabric degradation, areas where there is no stitching, no quilting yet the fabric is breaking down and forming little holes/threadbare areas.
Quite honestly I was heartsick about both of them. They both have literally 100's of hours of hand quilting work on them. While they are still usable they have looked pretty shabby for most of their lives. The fading issues on one of them started before I had even finished quilting it. The other shortly after I finished.
I swore off JoAnn's fabrics for good and really don't even shop there for anything at all as I find their pricing structure predatory (inflated regular prices so they can "trick" customers into thinking they are getting a deal by offering 40 or 50% off coupons).
In my mind if you are going to spend countless hours working on a quilt, why use inferior products.