Ubuntu Mono since it was in beta and I heard the designer from Dalton Maag — the typeface design studio commissioned to design it — give a talk about how excited he was to be able to create a comprehensive, carefully thought out, and truly free/libre font.

I’ve never seen another one that I prefer the look of, and now it’s imprinted in my brain. People love to crap on Shuttleworth / Canonical / Ubuntu, but there are a lot of great things they’ve contributed over the years.