Agree that Niche, Farmhaus (not a JBF winner, but one of the F&W best new chefs), and Sidney Street Cafe are the top for fine dining. I would also put Monarch in that category though when the chef is in the kitchen and can do a tasting menu. Other options worth looking into are Five Bistro, The Crossing and Harvest. Do not waste any time trying "St Louis Style" pizza as few outside of native St. Louisans find it edible. Pi Pizza (deep dish) and The Good Pie (neopolitan) are both good though. For breakfast, check out Half & Half. For wine, 33 Wine bar. Cocktails, Taste (formerly Taste by Niche). I really like Bogart's for BBQ.
For anyone coming to St. Louis here's where you need to eat: Niche Farmhaus Monarch Pi Sidney Street Cafe Pappy's Smokehouse I know St. Louis has a reputation for Italian food, but unfortunately it is more of a myth than reality. Sure there is the Hill where there are many Italian restaurants, but most are terrible in that all you find is red sauce poured over mountains of noodles. It's a product of hometown loyalty skewing reality. The best Italian restaurant in my opinion is Acero. St. Louis has some decent restaurants and it has come along way in recent years, but anyone coming from cities like Chicago, NY, SF will not find anything too enlightening. Farmhaus, Niche, Monarch and Sidney Street Cafe are the city's best and are all run by chefs who really care about what they do and are trying very hard to make progress.