Cotton will wear better. If you want to use the flannel it will last longer if you use bias cut binding. The reason bias is important is because the edge is not all one thread and it spreads the wear more evenly. For double fold spray starch heavly and press. I have had good luck with this method, made one like this for my daughter 38 years ago and she also used it for her (now 8 year old) daughter. Both girls have draged this quilt around and used it for years, and it has been washed to death, binding still good, quilt starting to show wear.