I have used flannel, cotton and homespun and never had any problem of them fraying past the seam line. I only sew one line of regular length stitching.
I make my sandwich...backing, batting and front fabric and stitch diagonally in both directions to hold the pieces together.
I have used all combinations of fabrics. Flannel & cotton, cotton & homespun, and some with the same type of fabric for front & back.