The batting I use depends on the project. If it's a kid's quilt or it's going to get a lot of washing, I like Hobbs 80/20 or Quilters Dream poly.
If it's for my bed and I am machine quilting it, I like Quilters Dream wool. It is thick, soft, and very warm, but sooooooo light. I have arthritis and I can't stand anything too heavy weighing on me.
If I am hand quilting it, I like Quilters Dream cotton Request--their thinnest lightest cotton. If I'm machine quilting, I like Quilters Dream cotton Select or Deluxe--their thicker cotton batting.
If it's going to hang in a quilt show, I like Warm n Natural--it isn't as drapey and the edges stay nice and crisp.
I detest silk batting, even though it quilted up beautifully. It caught on everything-- my clothes, my nails, my wedding ring--I had tufts of it all over the room. Looked like I worked in a Q-tip factory!