The airport shuttle bus line 1 and line 5 are still operating at that time. It is easy for you to get a taxi at the airport at that time, but I suggest you take the airport shuttle bus to the downtown city area first and then catch a taxi to your hotel. You'd better ask for the taxi driver to charge by meter. There is not an official taxi company in Guangzhou, but there are many taxi companies in Guangzhou. Among those taxis, the yellow taxis of the Baiyun Taxi Company, the blue taxis of the Guangjun Group and the maroon taxis of Guangzhou Transportation Group are the most reputed.