In terms of slower jobs, Dragoon, Black Mage, White Mage, Scholar, and most tanks that aren't Gunbreaker should be sufficiently slow.

Classes to definitely avoid would be Monk, Ninja, Samurai, Bard, and perhaps machinist and Summoner. Notably, i mention all of the melee DPS classes besides Dragoon because they all get GCD steroids that speed up their attack speed and tend to have a decent amount of oGCDs. Dragoon on the other hand gets no GCD steroids, and they don't really double weave oGCDs since their jumps are all too long for that, so they remain fairly slow even at max level.