Which website is cost-effective for booking hotels?

I booked it directly on where to go before. Later, I saw a friend book a hotel with public comments, and there were quotations and booking entrances for hotels such as Qunar, Ctrip and Tongcheng. He booked the same hotel on the public comment, the price is cheaper than other websites, and there are cash back discounts on the same trip, and public comments also have cash back. Originally1a hotel in 70 yuan for one night, the public commented on returning to 8.5 yuan and returning to 50 yuan on the same journey, so it was11.5 yuan, which was super cost-effective ~