Definitely nothing from JoAnn’s (although they have a “Luxe” flannel line or something like that now that might be better). I’ve made one flannel quilt, and I want to say the fabric was Robert Kaufman or something else “high end”. It is amazingly fluffy and cuddly.
When I started sewing, I used the cheap JoAnn’s stuff. Terrible in comparison (although it worked when I was just starting out and making small stuff for my kids!)