I have been to HK a few times. The last couple of trips I stayed at the Hyatt Regency in TST, and the Grand Hyatt. I would agree with shefgab that TST is a good place to stay - plenty to see and do, and accessible via MTR. When I was there the majority of hotels had shuttles to / from Kowloon station so you could take the airport express from HKG to Kowloon and then transfer to a small shuttle bus to your hotel. However, I am not sure if the shuttles are running post COVID.

I would also suggest getting an Octopus card - it's ideal for small purchases, things like the MTR etc. and means you don't have to fumble around for cash.

Lots of suggestions above in terms of places to go. I'd definitely recommend The Big Buddha on Lantau, as well as the tram up to Victoria Peak. Chi Lin Nunnery and Nan Lian Garden are well worth a visit as is Hong Kong Park. The mid-levels should be on your list too, with a lot of good restaurants either side of the escalators.

Also, you should also take time to view to Symphony of Lights Show which takes place every night. Best viewing points are from the Kowloon side of the harbour. Oh, and the Star Ferry is another must when you're in HK.