I really like Hobbs 80/20. I'm not sure about cost, but I have heard many rave reviews of Quilter's Dream cotton batting and Dream poly batting.
Years ago I made two quilts for children in the same family. One was made with 100% cotton batting, and the other was made with a no-brand polyester batting. I saw the quilts about 10 years later, after *many* trips through the washer and dryer, and it was very clear that the cotton batting had held up much better than the polyester batting.
From what I have heard about it, Dream polyester batting is the only poly batt I would consider using.