Luffy ---> Can do all the colors, but excels at Color of the Conquerer

Zoro ---> Color of Armaments, I see him hitting hard "cut anything"

Sanji ---> Color of Observation, I see him dodging a lot.

Usopp ---> Current weapon upgraded + devil fruit in weapon, also Jenny Craig

Nami ---> Current weapon upgraded + devil fruit in weapon

Robin ---> More knowledge. Knowledge is power.

Franky ---> Better tech for his cyborg body, no reliance on coke.

Brooke ---> Something involving summoning or musical attacks?

Chopper ---> New forms, control of monster mode.

edit: I'd laugh if somehow Ussop unlocks Haki, or is able to use it. But it would make sense if every single SH crew member excelled or used at least one of the colors because it would make them a pretty strong team overall.