Gutermann thread is fine. Stay away from Sulky cotton as it has a short shelf life and breaks easily. Poly threads will last longer, but remember that thread needs to be kept out of the sun light. Egyptian cottons are good. Stay away from Coats and CLark. I really like my blade sharpener. I think I have a True Sharp. It does 3 different sizes of blades. It is an investment. The first one on this link is a good deal and no shipping cost:
http://www.amazon.com/gp/offer-listi...&condition=new