Cotton is not what I call a 'warm' fabric. It takes forever to warm up on a cold winter night!
Just recently bought Hobbs 80/20, so don't have too much experience with how warm it is.
I have used a neutral colored fleece for batting many times and then used flannel as the backing and really like that combination.
If a quilt is heavily quilted, then it won't have too many places to trap heat, and therefore not feel warm.
If I ever get around to making a quilt for myself, it will be double batted and not too heavily quilted. It's on my bucket list...