Wow, talk about learning something new every day, so many things I didn't know.
I have used all kinds if batting, but my preference is warm and natural, I like the feel, there is no smell, you can iron on it, and you don't have to quilt as dense. But, I also like the fact that it is natural, and is not made from petroelum products. I rarely use poly because of that, but I did use it when I did my first trapunto project, because that is what everyone suggested. It looked beautiful, but it was a wall hanging, and no one would be bundled up in it. I only do machine quilting so so many things that would bother a hand quilter are not important to me. Another reason I don't use poly is that my husband is a asthmatic, and he swears he can smell the poly, and it bothers him.
I felt some of the bamboo batting, I think I would use that in a instant, because it feels like silk, and it is very green to the environment. That is very important to me. But it is so expensive, there is no way I could afford it with all the quilts that I make.
I have never heaard of the batting made from plastic bottles.
Like I said, you learn something new everyday. Thank you all for all the info.