Mark Simonson, a type designer who writes about typefaces, including the Anonymous Pro coding font, Arial versus Helvetica, and period type in movies.
HN commenters recommend his free Anonymous Pro monospace font and cite his article on Arial's origins as an excellent explanation.
I was under the impression that Arial was a cheap knock-off of Helvetica. They took a similar font and reshaped it so it could stand in for Helvetica.
Clearly this is uninspired, much like a KDE theme trying to recreate Mac OS X. There's no actual law that says such a knock-off must be inferior to the original but a) it's off to a bad start, and b) even if it ties with the original it's got the taint of being a rip-off motivated by greed.
The full history of Arial, from a link someone else posted:
http://www.ms-studio.com/articles.html
Note that Red Hat has in turn commisioned a font that is "metric compatible" with Arial: http://en.wikipedia.org/wiki/Liberation_fonts
It will break iBooks as people design beautiful standards-compliant ebooks that look great in other readers that support standards.
And yet, the author shows an example of proper behavior using Arial for the book’s body text, and Trebuchet in a garish red to mark up the screenshot. There are many beautiful fonts, but these are not two of them.
Edit: see http://www.ms-studio.com/articlesarialsid.html as to why Arial is so inferior to it’s predecessor, Helvetica.
I prefer the coding font Anonymous Pro (has nothing to do with the hacktivist group) - it's located here and it's for free.
http://www.ms-studio.com/FontSales/anonymouspro.html
Personally, PragmataPro looks too condensed for me. It is probably more "economical" to use condensed fonts, but to me, it is really not very readable.
There's an interesting story behind Arial; it was developed as part of a PostScript clone back in the days of Adobe's tight control over the Type 1 specification. Microsoft then threw gasoline on the Arial fire by bundling it into Windows 3.1, purportedly to save licensing costs.
http://www.ms-studio.com/articles.html
I really like Anonymous Pro, 11pt font, 0.9 linespacing on my 1440x900 mac. Looks good with light AA
http://www.ms-studio.com/FontSales/anonymouspro.html
edit: it sort of has serifs. kind of. well more than most sans fonts
Note that Arial is not based on Helvetica, it is more like a cousin of Helvetica. Arial's ancestor is Grotesque 215. There's an excellent article about that here: http://www.ms-studio.com/articlesarialsid.html