Langham is in a different (better) class than the W and Icon. But all 3 hotels have their good points, so depends on your priorities. Langham will be more luxurious. Personally I like the Langham Place in Mong Kok which is now renamed Cordis (too much confusion having 2 hotels with Langham in the name a mile apart), they have a very nice "apartment" style suite which has a full kitchen that comes in useful and rare in 5-star hotels (they want room service instead).