Paris remains one of the great food cities in the world, though its dominance in fine dining has been challenged in recent decades by London, Copenhagen, and Tokyo. What Paris does better than anywhere is the everyday meal: the neighbourhood bistro, the brasserie, the zinc-countered cafe serving a tartine and a café crème at 8am.
French restaurants traditionally offer a prix-fixe menu at lunch (two or three courses at a fixed price) that represents the best value in the city. The same restaurant charging €60 a head for dinner might offer the same kitchen's cooking for €20 at midday. If you're on a budget, make lunch your main meal.
The great concentration of good restaurants has shifted east. The 11th arrondissement — particularly around rue Oberkampf, rue de la Roquette, and the streets off rue Saint-Maur — has become the most dynamic dining neighbourhood in Paris, with a mix of traditional bistros, natural wine bars, and chefs doing creative French cooking at reasonable prices. The Marais, Saint-Germain, and Montmartre all have good options but prices are higher for quality that is often lower.
For vegetarians, Paris has improved considerably since the early 2000s, though it still lags behind London and Berlin. Most modern bistros now include vegetable-forward dishes; dedicated vegetarian and vegan restaurants have multiplied in the Marais and the 9th and 10th arrondissements.
The boulangerie is the foundation of Parisian eating. Bread here is genuinely better than almost anywhere else in the world. Buy a baguette from a good baker (look for the sign artisan boulanger), add cheese and charcuterie from the nearest market, and eat by the Seine — this costs almost nothing and is one of the great eating experiences Paris offers.