I use 6 for longlining and 10-12 for pulling cranks so I would say 8. That is mono. You might get by with 6/20 braid. I use the same rods a lot but not the same reels.
i use 30lb braid for cranksand 6lb mono for longlining jigs,i agree with mrdux though i use the same rods but change the reels out.I want to have a set of rods for each by the end of the year where i dont have to change them out.