i also have a bernina 440 and i worked at a lqs..so i had an opportunity to try a variety of quality threads..i found aurifil to be the best..my machine loves it...lasts forever..will not break and no lint buildup either...i would suggest you try 1 of each..such as mettler..sulky..presentia..and so on..you willo be able to judge for your self..good luck..and nice machine you got there