Comment by duopixel

Helvetica on Windows is terrible, see https://github.com/paulirish/html5-boilerplate/issues/42. This is because Helvetica comes from Linotype instead of Microsoft, and they care more about print than screens.

Arial might not be a good typeface, but as a font it's pretty damn well hinted for screens.

Except for Minion Web and Myriad, I haven't seen a really legible web font from Adobe that is usable at 11-15px. Heck, even Typekit uses Georgia/Arial for long copy.