When it comes to conventional optics it for sure is 6-24x72.
There is no reason to just use 6X because you can see better at 10X.
At 10X you have 7,2mm exit pupil and the scope is brighter than any 56mm scope at any setting for that distance.
Trijicon ACOG is not to be considered a night scope, not with that objective and no with 65% lighttransmission, and Aimpoint can never be a night scope either as it's stealing quite lot of light.
It's easy to think to much theory, but try it instead.
I have practically testet is quite a lot and I do mostly of my nighthunting with 6-24x72.
Some months ago we tested the low light capabilities on Burris and Zeiss Rangefinding scope.
We had a hare on 140 meters and a fox at 30 meters.
30 minutes after we no longer could see the hare in the scope we could still see it in the -72mm.
Some years before I had tested on a hare at 150 meters and the fox at 300.
This was in late september.
We tested Zeiss 6-24x56 and 6-24x72 against each others, and the 72 won with 15-30 minutes depending on the shooter.