For me, the first test of any font for coding is how well it distinguishes between the characters 1lIO0, along with overall legibility. I don't give too much regard to how pretty or pleasant it is, though personal preference does come into play here.
I've always favoured Lucida Console on Windows, now mainly out of habit.
I loved consolas on windows, but apparently it's proprietary... I use Inconsolata (the closest approximation, and a very nice one) on Linux for everything (I made it my system default). Inconsolata is nice. I believe it was actually created for programming with.
It really sucks when a font gives you a barcode when you have character sequences like this: Il|1
or you can't tell the difference between a O0 in a font...