I've been using the Connecting Threads Cones, but I'm thinking of ordering some Aurifil. Even though I clean out the bobbin area almost every time I switch bobbins, the sewing machine repairman scolded me last week. There was so much lint in the top part of the machine that the needle bar wouldn't slide. He told me that if I use my machine a lot, I needed to have it cleaned at least once a year. He was pretty surprised when I told him only bought it 7 months ago!