The Precursors
Several major classics were collected in an excellent anthology by Iain McLean and Arnold Urken (1995). Furthermore, McLean and Urken wrote a remarkable introduction that is one of the main sources of this entry as far as pre-Arrovian social choice is concerned.
Even if both Plato and Aristotle’s views regarding the goodness of the various political systems could have been discussed here, since it seems that, for them, the ideal would
be some authoritarian regime - oligarchy for Plato and monarchy with some kind of benevolent dictator for Aristotle with as objective the maximization of the happiness of the state as a whole, a theme related to both Bentham and Arrow - the standard (but quite recent) usage to consider Pliny the Younger as the first author to deal with a social choice problem is followed.