Generally the GM has scouting reports, knows the makeup and needs of his team, and has a forecast of the marketing value of the players available.
Citizens have empty promises and propoganda. They can research history and patterns for candidates. But many choose to follow tradition or mass support rather than understanding the details.
If you are make informed decisions it is more difficult for the citizen. But if you look at how each approach it, over 90% of the time it is the GM.