Horatio welcome to the QR forum.

On the 787 rows 2 to 5 have identical EF seats so there is no difference in comfort. Some prefer row 2 since they feel that they have a better meal choice/earlier meal service there whilst others prefer row 5 because they feel it offers slightly more privacy than other rows due to the bar behind the seats. The bar is almost never used as a bar but it is where people gather to wait for the toilets. The toilets are far enough away, and partly shielded by the bar, as to be no problem.
If neither food choice or privacy are important to you then rows 3 and 4 are also good.