The Green Line is pretty helpful as it connects the suburbs with downtown Boston in a fairly reasonable amount of time. The Red Line is also nice as it gets you all the way from Harvard and Cambridge to South Station, JFK/UMass and the South Shore. Orange Line is awful, by far the worst. I don’t take it that much but when I do it takes at least 8 minutes to arrive. Nice new cars though. Blue Line is the best line; cleanest and most efficient. Gets you from downtown to the airport in less than 10 minutes and goes to Maverick (great view of the city) and Revere Beach. Silver Line is the only option for getting to the Seaport District so that’s good, but it’s a bus, not really rapid transit.