We are currently comparing all the major web sites to find the most consistently lowest prices and at the moment, HotelsCombined appear to offer the best rates.
Not only the best rates, they also offer ‘hotel brokers’ who hold ALLOCATIONS at hotels so for example when the Marriott in Copenhagen was fully booked on the Marriott.com website, three rooms were available through GTA Hotels. We’re also comparing payment methods, for example, Booking.com allows payment at check-out rather than forcing payment in advance. This can be important for business bookings.