have lived in both places, all I can say is Singapore is much cheaper over all.
property in HK, is way overpriced, and mostly old and worn out. Singapore is half the price, if not more, you get more space and better condition
cost of living, most people say the same, although i think it cheaper in singapore.
although cars are expensive in singapore, cost of carparking in HK is crazy
also, with Singapore, you have so many cultures thne it is easier to eat in hawker places where as in HK, its all chinese. you eat western food in resturants in HK, its very expensive .....
stay in singapore lah !