You grab a bunch of fonts, try all the monospace ones, find one you like, and go with it. I use Liberation Mono everywhere. You might want to give Oxygen-Mono

You grab a bunch of fonts, try all the monospace ones, find one you like, and go with it. I use Liberation Mono everywhere. You might want to give Oxygen-Mono a shot just for kicks since its the "kde" font, but having used both I still like my Liberation.