I've been using Monaco for Powerline for quite a long while now. The main issue is that most of the builtin proportionally-spaced fonts have some glyphs which

I've been using Monaco for Powerline for quite a long while now. The main issue is that most of the builtin proportionally-spaced fonts have some glyphs which are difficult to distinguish. Monaco gets the job done but other people prefer slightly different glyph styles or want to make their own fonts, more power to them.