I'm arriving in Guangzhou at 22.00. What's is the best transport to go to Sherton Hotel Dongguan?

Do you mean the Baiyun Airport?
If yes, there are still several long-distance buses at the airport that can take you to DG Wanjiang South China mall city terminal. The schedules after 22:00 are 22:30, 23:00 and 23:50. And the pick-up station is located at Gate-A5 Arrival Lobby. It takes around 100 mins. The ticket fare is CNY 54 per person. After arriving, take a taxi to your hotel directly. The cab fare is CNY 80 to 90 at night.