THE best places in terms of quality, in my opinion, have to be Le Gavroche (for classic, high-french, Michel Roux cuisine), and Gordon Ramsay in Chelsea (what 3 Michelin star food should be). Gordon Ramsay is much, much more contemporary in it's cuisine and decor; but Le Gavroche is a gastronomic institution, and undoubtedly one of the most important restaurants in the development of London's now famed restaurant scene.
Two places to eat before you die!