For what it's worth, we ate at some great restaurants in Paris, but this was my favourite, by far:
Bistrotters Paris
Per TripAdvisor, they are
currently rated 18/13,991 restaurants in Paris - you will definitely have to make a reso if you want to attend, but if you want truly outstanding food in a non-pretentious, non-Michelin atmosphere, I would highly recommend it.
When we were there we could not get a reso for dinner, went for lunch - a great option as it's the exact same menu and pricing for both lunch and dinner. Just make sure you go with room for a 3 course plat du jour style menu.
Mark
Edit:
They actually had this on the menu while we were there... mmm, fond memories: