>>96479640 (OP)
If it's CoC 7e vs Delta Green 2e, I would say it's between allowing your players to push-reroll or not. CoC 7e's push encourages for more risk taking, but also makes the tempo and tension of the scenario erratic as the GM add more consequences to their actions which you have to keep up with. DG2e has a much more binary fail or pass skill check which is easier to keep up with but not as cinematic in tone.
Aside from that the other major difference is DG2e's combat system which IMO is better (but doubt you'll use in this due to the nature of the campaign antagonist), and the psychological bond system which allows you to ignore some insanity at a cost of ruining the PCs relationships.
DG2e is also by default modern as a setting, so if this is like the vidya modern times I say the better choice is DG2.
