I mainly use Warm & Natural now. I used to use poly, but it doesn't hold up as well for a baby quilt that gets washed frequently.
One thing to consider when deciding is how far apart you plan to quilt. If you are quilting further apart, you need a batting that can handle it. I think Warm & Natural says 8" or 10" apart, something like that. I've seen some that say a lot less than that. They would require heavy quilting. That might be too stiff for a baby quilt.