Which transportation is best to take from the HKIA to imperial hotel, tsimshatsui, thank you

The best way is to take the hotel shuttle bus, which will pick up you at the airport you and take you to the hotel directly. It costs 130HKD per person.
Or you can directly take the airport shuttle bus A21 and get off at Middle Road, Tsim Sha Tsui. Then you can walk to your hotel.