Gold crowns last the longest but you should'nt get them if you have mercury fillings because you will relese more mercury if you have gold in your mouth. Your Amalgam filling probably caused your tooth to break. You could get a ceramic onlay instead of a crown . It is similar to a crown but ,unlike a crown, when you get an onlay, healthy tooth structure is not removed.Your tooth will last longer and onlays are far less expensive than crowns. Frank Jerome DDS talks about why onlays are better for teeth than crowns in his book Tooth Truth.