75のほうが良いそうです

現物を見たわけではありませんが、
//www.flyertalk.com
/forum/miles-more-lufthansa-austrian-swiss-other-partners/
1079359-first-a380-flight-nrt-10.html

Seat 75AC and 75HK (which are in front of 76BC and 76JK) are really good seats
with lots of room being in front of the emex* door. The position of seat 75A
and 76K make the seat 76A and 76K have plenty of leg room in front of it,
especially the exit doors do not block the area (no protruding part of
the door like on 744).
* emergency exit

In this case you have take the exit-row 75. There is plenty of space.
Also 50C and 50H, 60C/H and 88C/H are quite good for long legs,
but there is the "risk" they put a bassinet there.

As I recall, for 60 C and 60 H, as well as 88 C and H, the wall goes
all the way to the aisle. 61D and 61H have the wall all the way to the aislelso
（意味不明、lsoは余計？）.

Yes, I do agree that the best seats for log legs persons are the emergency exit
rows 75AC and 75 HK (two seaters). Next best would be 76A and 76K. Third best
would be 53D and 53G which has advantage being in front of the plane,
and would be able to deplane first.

あとは、生き字引みたいなかたの登場を待てばわかるでしょうが。