Warriors receive their best Attack bonus from their Strength stat. Stamina should be chosen as their secondary for the Physical Defense, Hitpoints and Hitpoint regeneration bonus. When judging whether to use a +Physical Attack attribute over a + Strength stat, divide the +Physical Attack amount by 2. If this value is greater than the potential Strength bonus, then go with the +Physical attack, as the 0.2 Hitpoint bonus from strength is negligible.
Unlike the other classes, Scout does not see a huge bonus to attack power from Strength or Dexterity. In order to maximize DPS, a scout will want to make +Physical Attack power their primary stat, followed by +Dexterity then +Stamina.
Rogue benefits most from +Deterity items, though like the scout, their bonus is minimal. In many cases, secondary stats to focus on will be a tie between +Strength and +Physical attack. +Stamina is always a solid third stat choice.
In order to maximize damage output, +Intelligence. +Intelligence provides both +Magical Attack as well as +Mana Points. Stamina and Wisdom are also useful stats to have here. As you find yourself no longer running out of mana, consider dropping Wisdom and going with straight Intelligence and Stamina.
+Wisdom will benefit you from a healing and defensive standpoint. +Intelligence will increase your Magical Attack, but your priority should remain with +Wisdom and +Stamina.
Knights should focus first on +Stamina, then +Wisdom for the increased mana pool size and defense. Special attention should be paid when choosing between +Strength and +Physical Attack power items, as in many cases the +Physical Attack will be more beneficial than an equal level +Strength.