Ent or plastic surgeon for septoplasty as well as nasal polyps/cysts and fungal sinusitis?

ENT, definitely. An otolaryngologist (ENT) is specially trained in the function of the nose. Correction of a deviated septum is done for functional, not cosmetic reasons generally.
ENT. I would see your friendly ENT surgeon first - as it is important to address the medical issues.
Surgeon. Usually ENT surgeon for polyps/cysts and fungal sinusitis. Plastic surgeon for aesthetic/cosmetic nasal surgery.