I've done the E to Sutphin and then on to the Airtrain to T7 from the Upper West Side (103rd and Central Park West) and the only part of the trip that got me was the long walk between Sutphin and the airtrain. I've done cars in the past from Manhattan to JFK and I've had anywhere from 1hr30 to 3hrs. I'd take the metro any day of the week now.