my go-to is Hobbs 80/20, either white, natural or black (if the back & top call for it--usually it's natural). I love wool bat, especially if there is applique (or a panel) that needs the faux trapunto treatment. Then I will often double bat with 80/20 and a wool. Hobbs Tuscany is my favorite.
I also used QD poly in black for a recent doubled quilt and loved the hand of it and will definitely purchase more.
I also recently bought a bamboo bat at a show and anxious to try it out.