Luckily, our friends at ShowScoop—an app that allows you to rate the quality of concerts you've hit up, letting others know which artists put on a good show—has you covered. They've taken the artists playing the festival and ranked them based on their ShowScoop ratings. (Meaning that the ranking is not necessarily the best artists, just the ones with the best catalog and stagecraft.)
It looks like the ambient pop weirdos, Sigur Ros (I say that with love) have topped them all.
In case you were wondering, yes, I think Ghost Tupac was robbed.