Dan Benjamin on monospaced programming fonts for Mac OS X. A few observations:
Unlike Times and Times New Roman (which I can’t tell apart even under scrutiny), Courier and Courier New are very different. Courier New is anemic, so thin and wispy that I find it hard to believe anyone can bear to use it for anything.
I still use Monaco 10, not anti-aliased, for nearly all my programming and writing. Could be that I’m old and curmudgeonly and that’s just what I’m used to, but I like to think that the whole point of using a monospaced font in the first place is to aid in character-level precision, and non-anti-aliased pixel fonts render characters more distinctly.
To my eyes, Consolas is the best anti-aliased monospaced font.