Everything will be based on mid-tier catch up gear:
Ambu+2
AF+4 (kill an Omen mid-boss is a very low bar to get access to +3 every job, Limbus isnt difficult either)
Relic+2 (Enter dynamis on job, I think 100 kills is a bit higher of a bar to do solo, hence stopping at +2)
Emp+2 (I dont think 10k muffins and a sapphire is that high of a bar)
Anything from pre-Selb HTMB's
UNM loot, including augment
Escha loot (is this too high of a bar?)
Nzame set
Snapshot:
Head (+7): "BIS" for snapshot on COR, but if you've capped it, you'll want rapid shot, and emp+2 has +RS16. RNG has Emp+2 for same snapshot.
Body(+9): BIS if were ruling out Oshosi Vest (+12). Again, we come back to snap vs RS. Rng has Emp+2 (which Velocity Shot is calculated separately), COR has AF+4
Hand (+9): Carmine+1 has Snap+8 and RS+11, so its BIS for strictly Snap, but Carmine+1 is better because of RS.
Leg (+8): RNG has AF+4 with +15 , COR has Adhemar with +9 and RS augment. Otherwise Emp+2 and Relic+2 both have +8. Oshosi has +10
Feet (+7): Meg+2 has Snap+10 right there.
midshot:
I cant imagine midshotting in any of this across the board. Ignoring the fact not one piece has StoreTP, every piece has inferior racc/ratk to Meg+2 set. Sure the set enmity down bonus might play a factor, but I cant imagine a RNG or COR using this set will run into enmity problems.
WS:
Cor AF+4 body has better wsd and accompanying stats for physical WS. Neither this nor COR AF+4 body have stats to make it nice for magic WS, I'd assume the "Magic Atk. Bonus"+54 on Relic+2 would be better without even bothering to estimate numbers.
RNG can make use of Body for WSD. If they've unlocked Jishnu, I'm not sure if the Crit+7 or WSD+7 from Meg+2 is better. I doubt that can even be answered without looking at the bigger picture.
They couldnt even give the *** boots Movement+18, god forbid COR's run a bit faster.
So
Head: Maybe good for COR for Snapshot, depending if you can cap it using other pieces.
Body: Good for RNG for WS. Maybe good for COR for snapshot if Oshosi not available.
Hand: Might be useful for RNG for Jishnu, if Nzame Crit+7 >> Meg+2 WSD +7
Leg: useless
Feet: useless
Feel free to chew this up. Might do another set analysis as "catch up gear", but the RNG/COR was obviously the easiest one to work with lol.