Join Date: Dec 2004
Location: Riding the rails
Programs: Japan Forum, Skyteam Elite Plus, BW Diamond Select, HHonors Gold, NWA, DL, NH
Posts: 1,936
I agree of all the possible transfer stations (if you are looking for ease of transfer from NEX to Yamanote) in my opinion Shinagawa Station would be the easiest to do it at.
The transfer at Shibuya from the NEX platforms to the Yamanote line is a bit long, and very few NEX stop at Shibuya to begin with.