I prefer the curly quotes above the non-curly quotes, as the non-curly ones are really *inch* marks.

In this case the best would be to use two back-ticks, to make the text fixed width, as this is a reference to some programmatic value and not a quotation.

In programming text we should use the inch-quotes, as that is what is used in the programming language.

Same holds for the ’ in words like *it’s*, that is a curly one, and not a *foot*.