I am a recent convert to hotels.com and find it very reasonable. For me the biggest advantage was the full price on the website inclusive of taxes. Booking.com was always cheaper but once you added taxes etc on it was dearer.that and the free night after 10 stays.

Don't be fooled though booking.com hotels.com and Expedia are all the same company. We booked a marriott recently and didn't realise I couldn't add my marriott rewards account details to it for status because it was done through expedia

Depends what you want I suppose. But we have also done two ba holiday bookings and the price they got the hotel for no one could touch that and it let us pay the flights and hotels up over a few months which was good.