I’ve used several fonts when I’m coding (usually with Xojo) and here are a few of my favorites:

Monaco

This font is installed by default on OS X. It is big and very easy to read.

Menlo

Also included by default on OS X.

http://en.wikipedia.org/wiki/Menlo_(typeface)

Source Code Pro

Adobe released this font around 2012 and it is my favorite. I’ve been using it pretty much non-stop since.

http://sourceforge.net/projects/sourcecodepro.adobe/

Source Code Pro in Xojo Code Editor

Inconsolata

This is what I used until I switched to Source Code Pro. It is a little smaller than other fonts at the same point size.

http://levien.com/type/myfonts/inconsolata.html

ProFont

This is the first alternative font I used. I think the others mentioned here are nicer.

I’m sure there are other great programming fonts that I haven’t yet seen. What is your favorite? Let me know on Twitter (@lefebvre).