Nowadays there're three classes of public transportation tools: Bused, subways,or Taxies。
Buses are the most porpular public transportations. The first reason is that buses are cheaper than others. second, buses are of pro-environment than taxis, and thirdly, buses costs least. But sometimes you may accounter traffic jam on buses.
Subways are new type of transportation tool and developed rapidly. the most advantage of Subways are no traffic jam.
Taking taxies is the complement way of the former two tools. Taxies can take you to anywhere you want.
I think we should select transportation tools according specific environment, for example on Monday, traffic jam always occur, so we can take subway to avoid being late. if you live far away from the subway station but near bus stop you may prefer buses. But if you don't know where to take buses or subways you have to take taxies.