Good idea to expand! Here, based on the jobs I play (Main MCH):
Scholar fave: Deployment Tactics - it may seem like a peripheral spell, but honestly is one of the strongest tools if you can play it strategically, which feels exactly what the Scholar fantasy should be, a good strategist.
Scholar hate: Seraph - Animation lock in and out leaves such a tight window to use the Consolation charges, it's really annoying to optmize its use, and it also create ghosting problems for the regular faerie. Plus it doesn't feel inspired at all - it works like a watered down SMN Trance.
Gunbreaker fave: Continuation combo. It's literally the only reason I love GNB other than the fact that is a tech-inspired job, which is the aesthetic I always go for in games.
Gunbreaker hate: Burst Strike and the fact that is a weaponskill and not an ability.
Ninja fave: Raiton - Feels visually and mechanically satisfying to end a mudra combination with that. Actually I think NIN is the job with most exciting buttons to press.
Ninja hate: Bunshin - Your big level 80 action being a fire and forget that is not even visually impactful... Feels like a slightly better Wildfire. Still brainless, that's why it's the most meh, for me.
Machinist fave: Auto-crossbow. The sound and visual is engaging. I wish they had this for the spammable regular AoE and something else for the Overheated variant instead of the boring Spread Shot, that doesn't even make sense with the type of firearm that MCH wields.
Machinist hate: Wildfire, because it's visually unimpressive and it's a brain-dead ability now. You just need to press 5 heat blasts + 1 weaponskill and you're done with it. This is basically the worst sister to Bunshin.
Dancer fave: Standard step - Yeah, it is a maintenance buff, but the huge bursty damage that comes with it makes it something exciting to push every 30s.
Dancer hate: Improvisation - The level 80 action is such a letdown, because it's extremely situational. Even Saber Dance feels more interesting than this.
Blue Mage (yes I'm adding this one) fave: There are a lot of interesting spells, but my absolute favorite is Abyssal Transfixion, simply because of the way it looks and the icing on the cake is the long duration paralysis.
Blue mage hate: Moon Flute hands down. I hate that the DPS optimization is tied to this piece of rubbish... It's such a bad design to have you literally do nothing for 15s. I'd rather have Moon Flute being a little weaker and with a cooldown, but letting you do your regular things for 15s, but with a heavy penalty in dps/heals instead.