There are five basic categories of responsibilities/abilities in battle in FFXIV:
Damage Output
Incoming Damage
Potency Enhancing
Potency Enfeebling
Restoring
Now if you were to rate each job as to how well they do each thing...which would come out on top as overpowered, which as balanced, and which as underpowered?
Damage output:
If you were to go by most people's assertions, the order of this category would go as follows: tie 1st Archer(burst) and Thaumaturge(DoT), 3rd Lancer, 4th Marauder, 5th Conjurer, 6th Pugilist, 7th Gladiator.
Damage Input:
This would be how much damage the class is capable of mitigating through absorption or evasion. Classes with heavier armor, taunts, and defensive skills/spells would score higher here. 1st Gladiator, 2nd Thaumaturge, 3rd Marauder, 4th Pugilist, 5th Conjurer, 6th Lancer, 7th Archer.
Potency Enhancing:
This would be potency buffs(increase damage/acc) cast on the individual or party. Classes with group buffs would be more valuable enhancers than classes with buffs primarily for the individual. 1st Lancer, 2nd Marauder, 3rd Pugilist, 4th Archer, 5th Gladiator, 6th Conjurer, 7th Thaumaturge.
Potency Enfeebling:
This would be potency enfeebles cast on the target. 1st Thaumaturge, 2nd Conjurer, 3rd Lancer, 4th Marauder, 5th Archer, 6th Pugilist, 7th Gladiator.
Restoring:
This would be adding to your HP, MP, TP, or Stamina bar by buff or drain. 1st Thaumaturge, 2nd Lancer, 3rd Conjurer, 4th Pugilist, 5th Marauder, tie 6th Archer and Gladiator.
By scoring each measure of contribution to battle by awarding 1 point for 1st, 2 for 2nd, and etc we determine a battle worth ranking system where a lower score means a higher overall battle worth.
Results:
Thaumaturge = 12, average of 2.4/7
Lancer = 15, average 3/7
Marauder = 18, average 3.6/7
Conjurer = 21, average 4.2/7
Pugilist = 23, average 4.6/7
Archer = 23, average 4.6/7
Gladiator = 26, average 5.2/7
Now, at least according to my observations, the Marauders, Conjurers and Pugilists seem to be the most well balanced classes. They fall in the middle of the range of data, and none of them have any 1 or 7 scores. Thaumaturges seem extremely overpowered as far as their utility goes, scoring 3 1st places and a second, scoring poorly only on enhancing. Lancers may be slightly overpowered, as they are relatively good at everything except taking damage. Archers may be slightly underpowered overall, as their only above average quality is doing damage (but don't expect them to get a buff). Gladiators are really only good at taking damage, making them the least versatile class.
If any on class needs a buff, it is Gladiator. If any one needs a nerf, it is most certainly Thaumaturge.