Luffy- fire fighter
Zoro- police officer
Nami- nursery school teacher
Usopp- graphic designer
Sanji- stylist
Chopper- grade school teacher
Robin- flight attendant
Franky- pilot
Brook- Detective 🕵️
Luffy would die pretty quickly as a fire fighter, not much of a career ahead of him...
Zoro would be an efficient cop, but prone to brutality. His career would be destroyed for abuse of his power at some point.
Nami would do good as a teacher for children, can't see anything in her character stopping her from doing good.
Usopp as a graphic designer is cool, I guess..? Visionary, maybe, but unpractical: would do good only if allowed a large budget.
I can actually see Sanji as a stylist, smooth and with a sharp eye for the new trends... But he would end his career with some harassment case.
Chopper as a grade school teacher? Hard to see him keeping an entire class of kids interested in his stuff. It's a no for me.
Robin would be an excellent flight attendant. She has the professional aura, plus she would be able to balance the detachment of an attendant with cool ways to make the flight less boring. A really good fit imo.
I can see Franky as a talented pilot. He could be a champion if he manages to not die on the track. Plus, a pilot that can actually
feel the car is very helpful to the engineers and the technicians.
Brook as a detective... No I don't see a bright future ahead of him.
Overall, the three most likely to excel in their careers are Nami, Robin and Franky (with some luck) imo.