I agree that taxi would generally be the easiest choice, given the OP's situation.
BUT... HKG taxi drivers can be a bit crazy. One time we were in a similar situation, arriving really late (like 11pm) with little kids. So we decided to cab it. Scariest cab ride ever. The driver kept falling half-asleep behind the wheel! He was swerving from lane to lane. We shouted at him repeatedly, he'd wake up again, and he'd say "okay okay" with a smile. Then a minute later, he looks half-sleep. We asked him if he was okay, shouldn't he pull over, etc, etc. He kept saying "okay, okay" and kept driving. That's the last time I've taken a night-time taxi from HKIA into town. This fall, we'll be landing late again and this time we're staying at the airport hotel and taking the train into town in the morning. I know this experience was an outlier, but still.