Tanks get both a silence and stun. There's very few instances where you need both, so you would take the one you need (or, have each tank take a different one).

The choice seems more to customize your build to the fight; there's definitely places where you never use Esuna, or you have little chance to DPS. What if everything (dangerous) is magic, and E4E can never proc? Why do both healers need Protect?