Danforth type anchors hold best in sand and mud. They also have, by far the greatest holding power power per pound. Bruce and manson type anchors have less holding power but thier detla like spade has a better likelihood of digging into a grass or rocky bottom. They also have far faster reset time when the boat veers. Fortress' advantage is that it's light and can be disassembled. So I have three... fortress for sand/mud bottoms and storm power. A bruce for overnights in more crowded anchorages and an old northill (like folding fishermans anchor) for rocky or kelp bottoms. Northills are rare I think serious cruisers like a heave folding or disassembleable fishermans anchor for their storm anchor. I keep two on the bow (Bruce and Fortress) each with its own rode in a split locker. Manufacturers make recommendations on chain for chain/rope rhodes. A rule of thumb has been chain equal to the length of your boat. Hanging a "killet" on the anchor rode about halfway down increases holding power and also allows a short scope in crowded anchorages. An old standby on the subject is Earl Heintz's book the complete guide to anchoring. It's dated info on anchor types. When going thru the calculations I found that the weak link was the deck cleat and I needed to replace it with a four bolt cleat and a good backing plate.