Looking at the bottom 20% of frames by cumulative usage, most of which I play often, a few stand out to me as potentially benefiting from a rework. Might have some bad takes, so feel free to tell me how you play them! Always happy to learn something new about frames I haven't clicked with.
Need a refresh
Atlas: very tied to weapon selection which makes SP Circuit dicy. I'd like to see more innate power on his kit, or a change to petrifaction that improves its damage buffing, maybe with armour removal.
Equinox: augment syndrome. Some of them could be passives or otherwise extended (e.g. Energy Transfer could work on Pacify & Provoke too). Major systems rework could let her mod Day and Night separately, which would be nice as they both like different stats.
Chroma: funny damage man. Got a good buff with Circuit scaling his Spectral Scream (but not Effigy! what!) into actual strong damage abilities. The "keep two buffs rolling" playstyle is bad though. Spectral Scream could be a one-handed single cast that shoots actually good projectiles. Would also be nice to have Vex Armour store its buffs for recast, for accessibility reasons. Let Elemental Ward be recastable. Otherwise give him an augment or a passive that lets Ward and Armour refresh on some condition. Why does Gyre get to have all the braindead pew pew fun?
Could benefit, arguably fine
Gara: due to how full and synergistic her kit is, hard to fit shield gating on her build without Decaying Key usage. Good at health tanking, but that has scaling limits. Mass Vitrify deserves a buff to bring it in line with how easy Snow Globe is to scale infinitely.
Oberon: his damage buffing is very conditional on enemies reaching his garden. Very harsh range (235%!) and strength requirements if you want a fullstrip build without giving yourself RSI by double-casting Hallowed Ground constantly. Reckoning being able to blind on kills within a duration would be nice. Renewal could benefit from shield generation due to how healtanking falls off.
Lavos: please give him scaling survivability without dipping into Muzzle Flash or Resonator, or Arcane Trickery.
Trinity: absolutely horrible to play with the agonisingly short buff durations; this one is definitely personal preference though. Might benefit from damage buffing such as EV applying a small damage vulnerability in its area, or Abating Link being a target-radial armour strip that can be recast.
Out of the other low-usage frames, who would you like see refreshed or reworked?
I main Equinox, but her entire kit could really use some tweaks.
Her passive is paltry if you're actually using Night4, but if it let you pick up health orbs without being hurt like Synth Fiber, it'd be pretty great.
1 decays instead of persisting across the direction which just kind of sucks. Duality can use archgun, which is a nice contrast to Wuclone, but is bugged to consume all reserves of archgun ammo and wastes time reloading.
If Day2 affected bosses and punched through overguard, it'd be perfect. Augment just doesn't reach far enough.
If Night3 wasn't such an energy sink, I'd use it. No comment on augment.
And 4 preventing energy regen hurts, because you always want it on. The augment ought to be baselined.
And if we were getting spicy, I'd go so far as to suggest that 3 increases Orb Drobs depending on which form - Day granting Abilities from affected teammates a chance to drop a red on kill, and blue from enemies affected by the night aura.