The Stafford is fantastic, especially the new Mews Suites. Absolutely beautiful. This hotel is often overlooked. Keep in mind there are 3 very different room types in 3 different parts of the hotel - Mews, Carriage/Cotswolds, and Main hotel.
Service is fantastic. Stuart Procter the GM is dynamic, with an excellent staff.
The Stafford feels like a historic London townhouse, which it is, that has expanded.

The Ritz is great too, just around the corner, with a completely different feel - larger, an original Cesar Ritz hotel, the kind of hotel that QE2 would choose (and did choose) for her 80th birthday party.

I love the location of the Stafford and the Ritz, in the St James area.

The MO - I really liked this hotel, rooms and all, but wasn't crazy about the location - the traffic and crowded sidewalks were a bit much.
Rooms are English/traditional, public areas are modern/Asian in feel.