it all depends on what ur fighting u wont be taking a blm to fight something that is strong against magic attacks or a dragoon to fight something thats strong against piercing attacks. In the end no job really out DD's the other because they have a need for different mobs. In the end it depends on loads of things what job does the highest DMG.

Like what mob ur fighting, what gear u have, how well you can play that job and use it abilitys well so you never have down time DPS. How well you're party works together and well you know your job.

Every DPS job in my eyes is equal there isn't any that can out DPS the other because each job has it need for the different fights.