I’m rating my current favorites.

1. Consolas 11pt (AA)
2. Bitstream Vera (AA)
3. Envy Code B 10pt
4. Lucida Console
5. Courier New 10pt*

*Not a programming font by definition but is lightweight and very familiar.

Programming fonts are featured to have a more condensed nature, so you could see more lines on your screen, better character disambiguation for common combinations: l1, o0, etc.

As a result I used to have Envy Code at the top, but after realizing it crams so much text it might strain my eyes in, lets say 3 years of prolonged usage, I went with Consolas and set it the highest size I could.

I admit I do sin and use Courier as the alternate font, since I’m not into anti-aliasing that much.  I am yet to find a replacement for Envy Code.

I’m also not sure yet if serifs are good for code readability.