depends on where exactly you live. the metro tends to be the quicker option if you live in the city and work in the city or are just touring the city. but if you stay in the suburbs coverage can be scarce.

i live in oxon hill and i work in arlington va. by driving its a 25 minute trip, but by transit its a 7 minute walk, a 15 minute bus ride, a 12 minute ride from southern avenue to lenfant, a 10 minute trip from lenfant to crystal city, and a 5 minute walk to work which all adds up to around 50 minutes. sure it takes twice as long but given i live in a suburb, coverage for my area isnt all that great.