Years ago I was told that they made different quality fabric using the same print for different stores. Nowadays, I don't see that at all. The fabrics that come from quality mfg all are the same. My rule of thumb is to hold the fabric up to the light. If I can see through it, I don't buy it.
On the other hand, I don't always buy the highest quality fabric. If I want the quilt to last for years, I buy the best quality I can find.