Healer and caster gear concern going forward

[Alahra]

Total Uniques:
Tank: 9
BRD: 5
DRG: 4
WHM/SCH: 3
BLM/SMN: 3
MNK: 2
NIN: 0

Thanks for the breakdown. Some of the numbers are slightly off, though (some of which you got before I finished up writing this).

Bard and Caster shared a model for Second Coil (one was red, the other purple). Tank's set for Syrcus Tower was completely unique and not shared with DRG or MNK (though their set was shared, yes). I'm with you on Void Ark: I don't consider the tank/DRG sets separate enough (the tank body still has the same basic look as the DRG body with its leg piece, so the overall aesthetic is nearly identical). But, it's debatable.

I think it's also probably worth it to consider unique dungeon skins, too (I'm sticking with the usual suffixes so I don't have to type stuff like WHM/SCH/AST/BLM/SMN, though a lot of the sets have unique names). Pre-50 dungeons aren't included since they typically follow the DoW/DoM model (though tanks do get one unique set here, the Cavalry Set).

i60 (Pharos Sirius): All sets were reskins
i70 (Lost City of Amdapor): Fending (reskin), Maiming/Striking, Aiming, Healing/Casting
i80 (Hullbreaker Isle): Fending/Maiming, Striking/Aiming, Healing/Casting
i90 (Snowcloak): re-used Myth gear, all unique
i100 (Keeper of the Lake): Fending, Maiming/Striking/Scouting, Aiming/Healing/Casting
i120 (Dusk Vigil): Fending/Maiming, Striking/Scouting/Aiming, Healing/Casting
i130 (Sohm Al): all used the same basic model with minor modifications
i136 (The Aery): Fending/Maiming, Striking/Scouting/Aiming, Healing/Casting
i142 (The Vault): Fending, Maiming/Striking/Scouting/Aiming, Healing/Casting
i148 (Great Gubal Library): all used the same basic model with minor modifications
i160 (Fractal/Neverreap): Fending, Maiming, Striking/Scouting, Aiming, Healing, Casting
i185 (Saint Mocianne's Arboretum): Fending/Maiming, Striking/Scouting/Aiming, Healing/Casting

Dungeons tend to have overall more shared sets, but there are a few unique ones here and there, which brings the tally to (with Gordias included, which you also added later):

Fending: 14
Aiming: 6
Maiming: 5
Healing: 4
Casting: 3
Striking: 2
Scouting: 0

The runaway winner is still Fending, obviously, which has more than twice the number of unique sets as the next highest, and seven times as many as the lowest (discounting NIN somewhat since they weren't around for as long). There are fewer unique Maiming sets than I had the the impression were unique, but they're still doing better than most of the other roles. Aiming is doing pretty well, too—they're in the best position after tanks.

Edit:

3.2 Tomestone Gear: Fending/Striking, Maiming, Scouting/Aiming, Healing/Casting

That brings the number of Maiming sets to par with the number of unique Aiming ones. I'm not entirely sure how the breakdown for Midas will go (as far as I can tell we haven't seen all of them yet). It looks like tanks get a unique set there from what we've seen (surprise, surprise). Raid sets normally don't have many unique sets (tank is really the only one who consistently gets them), so that won't change the overall pattern much, if I had to guess.

My general feeling, that it's usually Tank/Fending and then either Maiming or Aiming that gets the unique set generally holds true. Going by what we have now, Aiming and Maiing have one-and-a-half as many unique sets as Healers, twice as many as Casters, and three times as many as Striking.