I would say the one best thing about living in Hong Kong was the public transportation and the convenience of them. There are so many different options them being the MTR (metro), bus, minibus, trams, ferries, and taxis. With all of these you can practically get anywhere in the city.
MTR
For me the best and most used was the MTR. The MTR is a city-wide metro that can take you from one side of the city to the other within 90 minutes for less than €7. The only downside is if you are taking the MTR be prepared to be crammed into a metal tube if you are either going around the city during rush hour in the morning or night.
Taxi
Taxis can take you from the airport all the way to the other side of the city for around the same price as if you were to take a taxi for about 10km in Finland which is about €30. From my experience even without speaking Cantonese I never had major problems with taxis. Be careful though because in Hong Kong there are 3 different colours of taxi and each one corresponds to an area in which it can drive.
Ferry
Ferries are very useful for crossing Victoria Harbour which is the body of water that separates Hong Kong Island to Kowloon and New territories which is the part land area of Hong Kong. Ferries can also get you to the smaller islands such as Cheung Chau which is a wonderful small island with great beaches and history one being the Cheung Po Tsai cave. This cave was apparently used by a legendary Pirate named Cheung Po Tsai which the cave is named after to hide his treasure.
Tram
I would say that trams are more for sightseeing rather than convenient transport for a traveller. They are quite slow which means you have time to soak in the skyscrapers of Hong Kong Island which is where trams can only be found. The tram line spans from the eastern most side of the Island to the western most side, yet again for a very cheap price
Double Decker Bus
The double decker bus or KMB as it is known in Hong Kong is possibly the second most used form of transport behind the MTR due the amount of people that it can fit in it. Like the MTR the bus can get you around the entire city although slightly more confusing than the MTR there is an app that you can download that will let you know where you need to get off. This can also be a scenic view depending on where in Hong Kong you take the bus and I highly recommend sitting on the 2nd floor at the front for the best views.
Minibus
The minibus I would say is hardest form of transport to use as you need to know where you are going and there are no apps to help you compared to the bigger bus. One crucial bit of information for the minibus is that you need to tell the driver when to stop at a bus stop because otherwise they will keep on driving.
I believe that Hong Kong has one of the best public transportation systems in the world although that reason may be biased not having lived anywhere else for long a long time. It could even just be how small Hong Kong is. Even through my travels to different countries I have not yet found any country that has such widely available, cheap, and different forms of transport.