Depends on the wallhanging. If you want a lot of Quilting Definition a ( loftier) batting is required-- if you want it to be flat a thin batting. Also, if it will ever be laundered ...is some shrinkage ok? ( cotton) if not-- polyester... There is no right/ wrong; best/ worse: each project has its own ( need) use what meets your needs. Does the quilting detail determine a big part of the overall piece? Or it is the design, with the quilting just holding it together? When your hanging top is together you can determine which batting will be best for that particular ( picture)