I just flew JFK-DXB on a 777-300ER (with suites) in Y.

46A/B/J/K had extra legroom (noticeable, I'd say 2-3").

46B/J had a slightly misaligned TV so you are leaning into your neighbour to see your own TV.

I sat in 46J but 50J/K were empty (and didn't even show on the seatmap when booking seats) so I moved there. At 46K you can easily lean on the window and still store things on the side. By 50K this is impossible. I ended up using my laptop case as a 'base' against the window and piling pillows on top of it to sleep. Without the base, the pillows would just fall down the side and it's really awkward to try and sleep. Also, 50J/K are RIGHT next to the washroom (literally, RIGHT next to). I didn't mind though and they are very private. From 50K you can only really see your neighbour in 50J.