Link: http://adteputek.com/b2evolution/blog2.php/2009/06/03/what-makes-a-good-anti-seize-compound

Good quality anti-seize has lots of metal (active ingredient) and little grease. This makes it thick and pasty. Since metal is expensive and grease is inexpensive, poor quality anti-seize is often a can of grease with a sprinkling of copper flakes. An example of good quality Anti Seize is Anti Seize Technology Cop-Graf, it contains 39% Copper Graphite.