Str is by far the best stat, hit is just as good until you are hit capped, crit and expertise are the next best stats, but not nearly as good as str is, armor pen is only decent if you are going blood, haste is by far the most useless unless you are planning on going dual wield. DKs are actually a bit different than warriors when it comes to stats mainly due to a huge portion of DK damage are magical damage, so the stats that only benefit physical damage such as expertise/haste/armorpen are not nearly as useful for a DK.