Tanking is about threat control. It has nothing to do with DPS.
A good tank keeps the aggro on them and off the spellcasters and healers. A good tank forces aggro if somone else draws too much threat.
Neither a Druid or a Paladin has CLOSE to the threat control of a Warrior in Protection stance. (With or without a shield).
I have run so many instances with a "tank" being a Paladin, Druid in Bear Form, and even a Hunter's Pet. They all have problems with gaining and keeping the aggro. They tank about the same as a warrior not using Protection Stance.
So to answer your question, the Warrior is the flat out best possible tank IF they use Prot stance.
Anything else and the priest and mage better get ready to melee.
A good tank keeps the aggro on them and off the spellcasters and healers. A good tank forces aggro if somone else draws too much threat.
Neither a Druid or a Paladin has CLOSE to the threat control of a Warrior in Protection stance. (With or without a shield).
I have run so many instances with a "tank" being a Paladin, Druid in Bear Form, and even a Hunter's Pet. They all have problems with gaining and keeping the aggro. They tank about the same as a warrior not using Protection Stance.
So to answer your question, the Warrior is the flat out best possible tank IF they use Prot stance.
Anything else and the priest and mage better get ready to melee.