Which bus goes to Metropark Hotel Kowloon and Mong Kok?

will you start from the airport? If yes, here is the transport means:
To the hotel, you can take bus no. E21 at Airport (Ground Transportation Centre), get off at Mong Kok Market, Argyle Street. Then walk east around 560 yards to arrive at the destination.

To the Mong Kok, you can also take the same bus, and get to Sai Yeung Choi Street South Station. After arriving, walk south around 130 yards.