My 2 favourite hotels are the Athaeneum and The Langham. The former is a boutique hotel (got engaged there!) opposite the Ritz. The Langham is much more regal and a grand dame but not as stuffy and the Dorchester or the Ritz. The Langham bar has been consistently voted one of the best in the world, their drinks are truly one of a kind. Another favourite of mine that exudes pure class, but unfortunately have never stayed there, is The Connaught on Mount St. Their bar (and toilets) are also world class. The Corinthia also gets good reviews but in my opinion not in the greatest location. Hope this helps!