I don't think you could go wrong with using fleece or flannel.
I have a "picnic" quilt I made with denim for the backing, and cotton (4 patch) for the top. I used a piece of fleece as batting because I wanted it to dry quickly (and the denim would already take a long time to dry), as well as stand up to heavy abuse of being on the ground (pine needles, twigs, etc) and frequent washing. The quilt is very pliable.