Originally Posted by
William S
Narita Express is easiest and takes you directly to Shibuya. However it is probably the slowest train in Japan or at least among the slowest ones...
NEX isn't particularly slow, it just takes a less direct route. Skyliner cuts more or less straight eastward from Tokyo while NEX has to go south to Chiba and then back north to the airport. You can get a sense of the difference from this map:
http://en.wikipedia.org/wiki/File:Sk...eisei_Line.svg
That said, as noted in one of the posts above, the travel time difference to central Tokyo is pretty slim unless you are going to Nippori or Ueno.