Rows 62 and 64 upstairs are considered by many to be preferable as the window seats still have aisle access without stepping over someone's legs.

They are also therefore harder to bag as regular higher status pax often nab them at time of booking.

But truthfully all the seats up there are nice. Window seats also get side bins so it's one of the roomier BA J window seats (upper deck on A380 same deal).

Plus if you're in full geek out mode and want to go and ask for a flight deck visit before / after the flight, that's where the guys and girls at 'the pointy end' are located.