I use Hobbs Warm 'n Natural or Warm n' White, Hobbs or Quilters Dream wool, and Bamboo. It all depends on the purpose of the quilt.
JoAnns is a good place for Warm products. In fact, I lucked out a few months ago, I looked up the sale price on JoAnns.com (different entity than the stores) for Warm n Natural bolt (96 inch)and did the price match at the store. The online was way cheaper and tax worked out cheaper than shipping. I also lucked out going in when they were having a 50% batting by the yard sale and they had an almost full roll of 124" (someone had bought 3 yards of the 30 yd roll). I had never seen a 124" roll before and I like to make King size quilts.