There are 2 things I think they do in better in Hong Kong. (Not that we do everything else better here but these are the 2 things I think there is little debate required)
The first being the bus system. Singapore buses are infrequent and makes far too many stops. Quite a pain to travel on and most of us would take the subway anytime.
It takes an hour and a half for me to travel from my place to my grandma's place on a weekend and really, Singapore is far too small to warrant such travel time.
Hong Kong bus network is excellent - short waiting times during peak hours and most have very well designed routes.
The second is Genki Sushi. Genki Sushi HK serves fresh sushi and offers a vast menu, with seasonal specials.
The one in Singapore, if Genki sushi is still here in Singapore at all really isn't that good.
Each time I go Hong Kong, I'd frequent the Genki sushi near where we stay. Unfortunately, it is wildly popular with the residents in the estate and sometimes the queues are just too ridiculous.
I managed to have a meal there last trip and after a few photos, I kind of forgot about photo taking! So as you can see, the food is really quite delicious.