http://forum.bioware...-and-mechanics/
I'll give you my general recommendations: .
For Warriors, Strength grants Attack %. Raw Attack % from Offense slots is almost always the better option, because Strength also governs Guard damage, and too few enemies use Guard. Willpower raises Attack% for all classes by 0.5% per point, and Magic defense by 0.5% per point. In general (outside of Con), Willpower is the best core offensive stat to raise if you're looking for multiple returns on investment (Rogues are an exception).
In general, assuming a tank, HP is better at the start (so armor with Defense Metal slots are better). As you get further into the game, Constitution becomes the better option. You won't get as much HP, but 9 Con will give you 45 HP (5 HP per Con) and 4.5% Melee defense (0.5 per Con). On higher difficulties, damage mitigation will help more than raw HP which can be torn through, and mitigation always applies, whereas HP is only helpful when it's up. That said, high HP does increase your total Guard amount, but the difference between 9 con, and 80 HP amounts to a difference of 4 total Guard, so the defense is generally better. Utility is how you raise core stats, and Utility Metal for Con/Strength.
For Mages, they use Magic. Magic increases Barrier damage, and their Attack% by 0.5. Again, Willpower and Attack% will be better than magic.
Rogues are the odd ones out. Rogues use Dex to raise their Attack%, but it also raises crit damage. Because of this, Rogues can double dip, and get higher offense from Dex. That said, again, raising pure Attack% and Crit damage% will see better returns on investment, but Utility gear shouldn't be overlooked especially in the early game. Cunning raises crit chance 0.5 per point, and ranged defense. Because of this, their core stats can give you a big advantage in the early/mid-game before the Offense*3 schematics become available, and if you're not crafting, but using found gear, the best stuff is usually what raises Dex and Cunning.
Armor Pen has a limit (it reduces enemy armor by 1% per point), so even though the guide indicates it's great, you'll eventually see diminishing returns, and some classes, like Assassin, can get all they need just from their own passives. As for what's best, it depends on the class. Belt of Health is almost always the best option outside of the Black Emporium gear. Amulet of Cunning for most Rogues or Dex, Amulet of Con or Willpower for Warriors, Amulet of Willpower for Mages, or cooldown amulets for everyone (or on on Inquis, which affects the whole party).
For Rings, Attack%, Crit Damage, or Crit Chance for offense, or Ability Rings, especially ones that increase damage or duration.
Just as an example, for my assassin I may use: Cooldown Amulet/Amulet of Dex, Belt of Health, Crit Chance Ring/Crit Damage Ring, and a Deathblow ring (basic setup)..
Some classes, like Champion can go a long way with a little extra Attack%, because they have enough defensive options. Something like Artificer will get the most out of stacking Cunning and Crit chance as high possible. Reaver with Heal on Kill gear is beastly, and Templars generally want things that let them come off cooldown faster, and they can make awesome use out of Stamina increasing gear. If you have specifics in mind, we can try to find options that fit your team, and your playstyle.