OK, the truth is—I really like monospaced fonts. It’s very hard to design a good monospaced font, so I’m always impressed when someone pulls it off.
If you practice in a jurisdiction that requires a monospaced font, you can still do better than the Courier that comes with your computer. There are actually hundreds of monospaced fonts out there—it’s still an active area of font design partly because monospaced fonts are preferred by software engineers and technical writers to display programming code.
(Original) Courier. The default Courier on your computer is actually “Courier New”, a soulless reinterpretation of the original 1956 Courier design. The original is still available, and still superior. If you want to stick with Courier, why not use the best Courier there is?
Letter Gothic and Prestige. Two classic 1950s typewriter fonts, commissioned by IBM for their typewriters.
TheSans Mono and TheMix Mono. Two modern monospaced fonts, each available in eight weights with italic styles.
You could also try “Consolas” if you have Microsoft Office 2007 or later.
You might also try Bitstream Vera Sans Mono or its sibling, DejaVu Sans Mono. Both are free.
There’s also Panic Sans, which comes with Panic’s Coda programming application, Menlo, which is included with Mac OS X 10.6, and Anonymous Pro. All are designed with coding in mind, which means they’re quite nice on the eyes.
Good suggestions. Monospaced fonts for writing code are a little different than general-purpose monospaced fonts:
First, they’re optimized for on-screen use, not printed use.
Second, more attention is given to distinguishing ambiguous characters like cap O and zero (0/O) and lowercase l, cap I and numeral 1 (l/I/1).
Third, punctuation characters are usually chunky & distinct so that they’re easily visible.