like most fabric, there are different qualities of flannel. the one that pilled probably has some polyester in it...or a lot of polyester. All cotton flannel is definitely the best for softness and durability. even with cotton, you can find some one-sided flannel...look for the two sided kind for the best (in my opinion). There is also a big difference in the weave between poor and good quality - you can see and feel the difference between the two...just keep looking.