Red Mage can hold on to their gauge burst for 2 GCDs without losing dps, and then hold onto it 3-4 GCDs longer with minor loss in dps. They don't have to maintain their gauge mechanic and lose nothing in down phases other than a minor amount of potency on their procs. They have no dots, debuffs, or self buffs to maintain.

Other classes completely drop their gauges and have to ramp up dots/debuffs/buffs on phase transitions or death. Red Mage doesn't care.

Practically, Red Mage is the most consistent dps right now. Just don't kill yourself or others doing charges or backflips.