Most useful dps

[BlueMage]

Bard. Bard is always wanted. Always. There are fights where every DD takes their turn at being unwanted... except Bard.

SMNs lack burst, BLMs perform poorly when they have to move a lot, and melee aren't welcome by many parties in several fights.

There's no such thing as a Bard unfriendly fight. Bard will consistently perform well and put out good DPS in every fight in the game. Also, it gives one a kind utility in the form of their songs, and Bard has the most reliable silence in the game.

I say this as someone who plays all DD classes in Coil/EX content.