If I can't upgrade I prefer seat 38K or A. I generally prefer a window because I don't get up during the flight and mostly try to sleep (it's a good 14 hour flight, so you will get some sleep even in Y). Row 38 is far enough away from the main screen to actually be able to see it. I wouldn't go for any row closer to the screen and also wouldn't go much further back unless you don't care about the movies at all.