This is always going to be a personal choice. I'm guessing this was on the 787-8, where 7A is on the wing, whereas on a 787-9 the same seat number is before door 2L. On the 787-9 I don't think there is a better seat really. On a 787-8 then 3A/K is the obvious choice, but I would still go for 7A/K if not available. Obviously it also depends on the sun to some degree but personally I'm happy with the blind controls. If you want to be cocoon somewhere a bit darker and also a bit of extra space then 7E has a lot going for it. If you are normally an aisle person, which is what mmxbreaks indicates, then I can see the difficulty. The 787 is much, much quieter than a 777 so it's all somewhat relative, but there is more engine noise in row 7 on a 787-8 compared to row 3.