There maybe a topic on Nice already? But it's a hard word to search for at least with my limited technical skills.
Don't go to Chantecler. A little run down now that the old lady who owned the Negresco has died.
The usual sort of natural wine bars are pretty decent: La Part Des Anges is good, and does some decent charcuterie in a very convivial and relaxed atmosphere.
La Merenda is excellent: cheap bouchon type place doing uncompromising provençal and niçois dishes: one wine, cash only, no phone. The main courses on my visit were tripe, andouillette and daube provençale, very good starters of fried courgette flowers, ratatouille and that sort of thing. All very correct within the parameters of the dishes and the traditional methods used.