That's a very open question & without saying what means 'best' to you you'll either get 10 different answers or none. What is important to you - location, room size, facilities, hotel restaurants etc.etc. What may work well for a work week in the city, might not be as good as a touristy one. There are even significant differences between the 2 London Intercontinentals & no clear consensus which of those is best (I've not stayed at either as my London stays tend to be Crowne Plaza Kensington or more recently, Leicester Square Indigo). There's a good thread somewhere on here debating the 2 different London Intercontinentals.