I have a Gammill and use mostly Signature thread with no problems. I understand Gammills like Signature. I have also used Marathon thread, which I like alot, and wish they had more colors. It's not much more expensive than Signature, and I like the quality better. I recently bought some King Tut, but haven't tried it yet. I bought it to try to get a better color match for a specific quilt, and it turned out that the thread I already had on hand was best, so the King Tut threads are still unused.