Without knowing how many HH points you have, when you are traveling, what, if any, HH status you have or what your goals in London are, it's hard to make recommendations. I have stayed at the LXR Biltmore and Conrad and would recommend both. Each is good for different reasons, so hard to say which would be better for you. There is a Hilton Curio in Trafalgar Square that is supposed to be good, but hard to get on points and the base rooms are small. Hilton has a few other properties around London, so you are spoiled for choice, however the aforementioned three would be my top picks. I have reveiwed the Conrad and LXR on here.