That's always subjective, which isn't a great answer. I never really liked sans serif fonts for body text, but there are a few that have convinced me otherwise

That's always subjective, which isn't a great answer. I never really liked sans serif fonts for body text, but there are a few that have convinced me otherwise -- off the top of my head, Fira Sans, Lato, Open Sans, and Source Sans Pro are all good, and all available on Google Fonts to boot. (If you don't want to have any downloaded fonts, you're kind of stuck with either really lowest common denominator stuff or doing a font stack and being okay with fonts changing a little depending on OS. Calibri and Candara are widely available on Windows, but hit-or-miss on Mac and virtually non-existent on Linux, for instance.)