Another option...I've stayed at the Novotel Tung Chung several times before early flights out of HKG and always found it perfectly fine. The first time I stayed there it was 1/3 price of the Regal, and sure you have to take a 3min shuttle to the terminal but I've also combined it with visits to the Ngong Ping 360 which is walkable through the Citygate mall so it has its pros beyond just being cheaper.