It all depends on what you want out of a quilt. Are you looking for a lightweight or a heavyweight quilt? Do you want high or, low loft? Or is your quilt a piece of art?
If you want a heavier warm quilt with medium to high loft you might want to use a 100% cotton or an 80/20 cotton/polyester blend with a high loft that has been needle-punched. The benefits of using needle-punched cotton batting is that the batting will not separate or bunch up, even after many washings. You can purchase cotton batting with low, medium or high loft. The cotton/polyester blends have higher loft.
100% polyester batting gives a lightweight, high loft and holds up with repeated washings and heavy use.
If you are looking for lightweight and warmth you might use a 100% wool or a wool blend. Wool batting produces a lightweight quilt with lower loft and excellent loft retention. I use Hobbs Tuscany Collection which can be hand or machine washed. When washing use as little agitation as possible or wash in machine with no agitation. Too much agitation or steam could cause felting in wet wool. I have had much success using a front-loaded wash machine. Wool batting is available needle-punched. The wool gives warmth without the weight. The fiber breaths, allowing excess heat to disperse away from the body.
If you are wanting a batting for wall art, I would recommend using wool batting for the lightweight and the lower loft.