Loved this article. Amazing how such a subtle difference can cause such a big difference in visual impact
People who don't know the difference, and can't articulate it, will /still/ know something is wrong, even though they can't put their finger on it.
Helvetica is the winner. Geometry is much tighter, plus the kerning and hinting is far better, and you have the possibility of using the many faces in the family from ultra condensed, to wide, from light to black.
The biggest strength of Helvetica is its biggest weakness as well; it works with everything. Almost anything in any context can be written with Helvetica. In most cases though, it's not a particularly intersting choice, I could say, it's a bit boring to see Helvetica everywhere. Of course there are places where Helvetica is a very good fit; the New York Subway is one example of that in my opinion.