Ask HN: What is the best font and styling combo for readability on the web?

As I read HN I often come across personal blogs / websites that look great and are visually easy to read, but I change my mind on what is "best" all the time.

Admittedly this is a matter of opinion and the web is not short of opinions, but I'm wondering what users here have found are the most pleasant to read font and styling combinations?