I like 50 or 60 wt poly for all of the above. This wt in bobbin and top for pieceing takes very little room so the seams fold over easier when pressing. Quilting is both decorative and functional. For strictly functional 50/60 or monofiliment all work. If the quilting is dense, 50/60 gives the least build up. For decorative 30-12 and bobbin work provides the most visibility in art quilts and primitive look.