Toughness to cap (Unknown currently) -> Endurance/Spellpower -> Wisdom -> Hit/Spell Focus to tank cap (Unknown)/Dodge -> Strength -> Block/Parry -> Intelligence -> Dexterity -> Crit.
My reasoning behind the above list are thus: Toughness will reduce our chance to be crit by raid bosses and heroic/elite instance mobs. This will be our most important stat to cap in these situations, useless if running level 50 normal content as 1-50 normals cannot crit.
Endurance and spellpower both equal survival, endurance is raw health, spellpower becomes block and parry rating, as well as a major threat magnifier as most of our attacks use life energy which counts as spell damage. They will be on about an equal footing. Enchanting for endurance and spellpower will depend on the content you are doing. If you struggle to maintain threat, gear for spellpower (if hitcapped). If your threat is fine, gear for health.
Wisdom is our next important stat, as it provides MP10 and spellpower. It is slightly inferior to pure spellpower, but not by much. It is most likely that spellpower will be a secondary stat and that items with wisdom on them will also have spellpower. Wisdom should be enchanted for if lacking endurance/spellpower enchant options on that slot.
Hit to tank cap is in our third priority category along with dodge. Hit is an important threat stat and it has been stated that a high level of hit will be needed for raiding and instancing. Dodge shares this category because we do not get dodge from our spellpower. This means that it will always be significantly lower than our block and parry ratings and point for point it will be worth more than either due to a lack of diminishing returns. It is yet to be seen how much dodge rating there will be on chain items. Hit is worth enchanting for if you are below the cap. Dodge is not worth enchanting for unless there are no Hit/Endurance/Wisdom/Spellpower enchants on that slot.
Strength has reduced value compared to the other primary stats (excepting intelligence) but a higher value than block and parry rating on their own. 1 point of Strength provides 1 point of both parry and block. The only time it would be worth taking block or parry over strength would be if the combined block/parry and spellpower on the replacement item was higher than the voint balue of strength. For example, an item with 10 strength = 10 block and 10 parry. An item with 20 block or 20 parry would be equal to 10 strength. An item with 15 block/parry and 6+ spellpower on it would be better than 10 strength. Enchanting for strength could be viable, depending on what other runes are available for the slot.
Block and parry share an equal importance as we gain both from spellpower already. If they are on chain items they will be worth taking, but not to the detriment of any of the above stats. They are still worth more than intelligence however, as 1 point of intelligence provides a much smaller amount of benefit from spellpower than 1 point of either dodge or parry. Enchanting for strength is better than enchanting for block/parry, it really is sub optimal, but better than Intelligence/Dexterity.
Intelligence provides spell crit(threat) spellpower(Mitigation and threat) and additional mana. This might make it seem like a very powerful stat, but the actual increases it gives to these stats are tiny in comparison to gearing for the actual stat. It is a nice secondary stat to have on gear and should not be neglected, but you should not gear specifically for it. Do not enchant for Intelligence.
Dexterity is unlikely to be seen on chain gear due to the conversion abilities in the melee souls, but if it is it is worth taking over Strength or crit gear for the additional dodge value. However, it is not worth gearing for and should be replaced quickly, as the dodge value it gives is much smaller than the bonus received in a point to point value of dodge rating itself. Do not enchant for dexterity.
Crit and spellcrit are both at the bottom of the stat list. While they both provide extra threat it is inadvisable to gear for either. Do not enchant for crit.