In my city, I most frequently use buses, trolley-buses and trams.
In my city, I most frequently use the bus, trolley-bus and tram. (Here, only one "the" is necessary. It is assumed to refer to the following three nouns".)
If the student really wants to use a phrase including "transport", then perhaps:
In my city, my preferred forms of transport are the bus, trolley-bus and tram.