Role - Class (Jobs)
Tanks - Marauder & Gladiator (Warrior & Paladin)
Healer - Conjurer (White Mage & Scholar)
Damage Mage - Thaumaturge & Arcanist (Black Mage & Summoner)
Damage Ranged - Archer (Bard)
Damage Melee - Pugilist & Lancer (Monk & Dragoon)

The least played Roles tend to be Tanks and Healers. They are the 'Responsibility' Roles