A much more interesting question than "Arial or Helvetica" would be: "Which one looks better?" Then you could ask how well the answer correlated with Helvetica vs Arial.
This question is good for seeing whether people know what they're looking at, but the point of using one font over the other isn't to show you prefer the 'correct' font, but to be invisibly better than other choices in one way or another.
The problem is that there was a lot more effort put into the originals than their knockoffs in Arial. The originals were produced with a designed typeface - and typefaces are tweeked for size. The Arial knockoffs obviously used scaled up versions in several cases. The knockoffs didn't get the same attention to kerning either.
This question is good for seeing whether people know what they're looking at, but the point of using one font over the other isn't to show you prefer the 'correct' font, but to be invisibly better than other choices in one way or another.