I will never play Summoner again until it is restored. It was my second class/job that I took on before even reaching the praetorium (which I also will never play again along with meridianum since their identities were ruined- they should be restored to being 8 players at the very least- these 2 duties are/were the first time a player sees/saw 'Full Party', it's kind of a big deal with the story- thus I have also 'lost' MSQ roulette from my game and actually miss doing these) and used Summoner the vast majority of the time up to and through Shadowbringers, then it got deleted from the game and replaced with a joke that bears no resemblance. Ever since the replacement there has been a hole in my character's story, like my character has amnesia and only a few fragments of memories of what happened before Endwalker. The game itself will never be whole for me again until Summoner is brought back.
Also, Gunbreaker, which I also don't play anymore because it was ruined by increasing Bloodfest's recast from 90 seconds to 120, meaning you now have to do 2 or 3 more full cycles of 1-2-3 slash during that 30 extra seconds to build cartridge fills, making the job a whole lot more boring and grindy. Essentially Gunbreaker was turned into Red Mage without the magic.
Machinist was apparently already ruined before I started playing it, as I found out during levelling that the animations get replaced with ridiculous stuff. I loved Machinist before that started happening. Machinist is another job I don't play, but mostly because Reaper has taken over as my 'lazy job' that I use for smashing roulettes and other duties on cruise control/chill time. I liked the workshop/brown leather/factory work vibe that was going on in the early MCH days, hopefully MCH can be changed and maybe split into two different jobs, with Machinist going back to it's roots and more of it with tool-based skills and basicer technical stuff- then the crazy animations can be taken out and put on a new and different job.
Astrologian I am still new to, but stopped playing it around level 50 because I don't feel or see a connection between the card skills and the rest of the skills. I appreciate the distinction of Astro's 2 regen skills also giving some instant hp aswell, which WHM's doesn't do, so that's something good. Other than that though, I feel it's a modified white mage that needs more frantic button presses more often for no visible benefit (and the buffs are only 15 seconds!). I cannot see the extra damage my buffs are doing so it's like working overtime for no pay (or someone else getting paid and credited for my work!). Keyboard and mouse users probably don't experience this factor the way controller users do- it's harder and irregular to have to constantly target the right type party member for an extra reason than usual on controller (for a healer). I'm hoping that whatever rework is coming, gives Astrologian what I feel would be a proper identity, but I doubt it. I like the idea of using cards, but it's difficult to chew and flavourless in it's current form. It doesn't really matter if you apply a card to the wrong player, it's all the same really and virtually a placebo. However I respect that some people may like it as-is and may hate a potential full rework, so there's that.
Sage is good but I already read ahead and found out that the attack skills change colour from red to blue almost instantly, at level 72, so I won't be levelling mine at all ever (and in a game where you don't get to make many choices at all, choosing to not level a job has thus become a decision I *can* make, that gives a character some identity). Why would you make the job more bland? In a game where most of the effects are already blue. Will settle for a change where they now become purple, green, orange, yellow, pink. Anything but blue or white really.
Every other job is 99% fine don't mess with them. Be wary of continuing the path of ripping out the game's foundations (any part of the game) as longer term players will indeed become increasingly alienated by the game as a whole. The graphical rework by itself may have unintended consequences, but I am optimistic that it won't.