Following are the community guidelines (For broader Stack Exchange network at least) on how to choose a Dupe target:
Usually a recent question will be closed as a duplicate of an older
question, but this isn't an absolute rule. The general rule is to keep
the question with the best collection of answers, and close the other
one as a duplicate. If the selected target question is unanswered, the
system won't even let you pick it as a duplicate target.
If one question has great answers but bad wording, and the other has
poor or no answers but great wording, edit the badly-worded question
and close the other one as a duplicate.
If in doubt, close the more recent question as a duplicate.
The quality of answers is subjective which is why we leave it to community to vet and mostly we trust each others judgement.
In your specific case, As you say that neither have good answers but both potentially have the same answer, you should choose the one broader, better-worded question as dupe target and close the other one as its duplicate as Phantom42 suggested.
As you noted, in case both have answers, generally we tend to choose the one with better answers even if it is badly worded. As above quoted guidelines suggest, one should improve the wording of the badly-worded questions if it has better answers.
In any case, right now, this question has already been closed as duplicate of this one by community review as the target indeed looks like it is result of a more through research.