Any of the window pairs should be fine. Beyond that I think it comes down to personal preference over things like lavatory/galley proximity, facing forwards/backwards, and whether the aisle pax can see the face of the pax diagonally across the aisle in the center block (e.g. Row 4 are the only pairs where you aren't looking at someone, but are close to lavs and galleys).

I think Row 2 has somewhat restricted vision of other pax, but I forget.