I hope you can support my opinion.
The balance of the game needs to be reconsidered. let's not forget, we are on ending content, the main story is over, open to new possibilities. Allow jobs to be broken, to provide more party utility, buffs, and sense according to their lores.
I love Dragoons, Summoners, and Black Mage, I love Samurai and MAchinist
Make the tank's damage the same and big according to the content, it's okay to break them a bit, give the dark knight a healing ability as all other tanks do.
Dragoon should have their damage balance with reaper and samurai, okay samurai can deal a bit more damage, but you can for example add a party utility ability that does the same as the kaiten ability did but with all the party members.
Dragoon for me is great just balance it more with samurai, and also reaper the same.
Allow dragoon maybe, to summon a dragon partner that also deals damage, that is part of the lore of dragoons
Summoner, I think summoner needs more summons inside the rotation that it has, and to be more accordingly to the lore, you can add on the three-way rotation LEviathan, Ramuh, and shiva, and arcane summon could be odin, and you can change the LB to be a bahamut flare, such as it was on the coils, to make it better, increase the damage of all casters to be as close to melee, the same as to range, and allow to carbuncle has more present on the damage rotation, for example, make it auto attack, according to the player action, as for If you cast Ruin it cast a single damage spell that can go accordingly to the summon you did, for example ifrit, carbuncle does primal fire as the single target attack, if it is the aoe version allow carbuncle to do an Aoe version attack of ifrit, and so on, that will make summoner awesome, also, allow for the healing ability of summoner to be at least as a red mage, that is significant, because it stops working at level 25, and you use it no more, that will be a great way to correct that.
As for black mage, allow for lay lines to be a party buff that increases casting speed, for all players the same amount of time as it does and not a standstill ability, and also that increase speed of movement and maybe critical hit for 5 % that way Black mage will have utility not only on its damage, also add a healing ability that heals it overtime such as regen do, that could be great on it
As for machinists, well the same all DPS should have their damage balance to be close to each other enough to be playable on all content, simple as that.
MAchinist needs a party buff, it already has a party defense ability, but remember, it is the physical damage dealer of range it needs to have a critical hit buff for all the parties for at least 5%
Make it new, make it broken, we are on the ending content
This is my humble opinion on making some classes good again.
I know there are more people that know more than me, I hope they support this opinion and add more.
Thank you.