Well… All of the ASE stuff on Zer0, probably, since Decepti0n was one of the most spammable action skills in Bl2. Also, 300/90 because it would pair well with Decepti0n.
Maya might be well off with consec hits because
- She doesn’t have many straight-up gun damage skills and
- She can easily apply elemental dots
Krieg could do a variety of things. Consec hits would work rather well for the same reason as Maya, but I think provided decent scaling he could also make use of ASA novas and elemental crit.
Gaige would probably benefit most from bonus elements (because Anarchy really is all the gun damage she’ll ever need, just like Zane) and since her action skill is duration based, probably U/Rad.
Axton would probably love the 200% ASE splash considering he could just throw his turret at his feet and immediately pick it up again to refund some cooldown and end the Action Skill early.
Salvador is kind of an interesting one because of his high action skill uptime, so consec hits and 200% ASA gun damage, I guess. Possibly also elemental crit for off-hand shenanigans.
Lilith: ASE bonus elements, Consec Hits
Mordecai: Also ASE Bonus Elements, 300/90
Roland: Consec hits, ASA 200% gun damage
Brick: 200% ASE Splash (could potentially get triggered using the inventory berserker rage cancel)