You can get the Hobbs batting at Connecting Threads
www.connectingthreads.com
They have the 80/20, the polydown, and wool. Sometimes there's a pretty good sale.
Last winter when I was looking for a lot of warmth I made a quilt using wool batting...nice and puffy and warm!
I've also used bamboo (actually a bamboo/cotton blend), 100% cotton (Dream Cotton), W&N...and for certain things the "flat" type of polyester (e.g., for table runners and handbags). I have noticed that if I use cheap poly batting (the puffy kind) it does flatten over time. I think I'll try the Hobbs Polydown next.