Liberal republics offer many advantages over other systems, including and beyond freedom.[i]
They are less corrupt. Opportunities for corruption, political and personal, are reduced when equality under the law and freedom of the press backstop accountability through elections. As the right-hand side of the figure shows, corruption drops off sharply as countries become fully republican and liberal. This implies that even small amounts of backsliding by advanced democracies can invite big increases in corruption.[ii] For example, moving from the position held by the U.S. in 2016 to the position held by Hungary would double the U.S. corruption index from 26 to 52.
Excerpted from Democracy is Precious.
[i] Much but not all of this paragraph comes from Holmberg, S. and Rothstein, B. (2014). Correlates of the level of democracy, The Quality of Government Institute, University of Gothenburg https://qog.pol.gu.se/digitalAssets/1510/1510618_correlates-of-the-level-of-democracy.pdf
[ii] The relationship between democracy and low corruption holds over time as well. See for example Lederman, Loayza, and Soares (2005). Accountability and corruption: Political institutions matter. Economics and Politics, 17(1):1-35.