Read the "professions" section in the guide at the beginning of the thread and then decide for yourself.
I have on me DK mining and blacksmithing but I want change mining to engi. When new expansion start engi is better than mining because it gives gloves enchant + epic head, mining give only stamina. But in late game what would be better? Dodge after DR or always the same health . Avoidance vs EH. What would you choose?