Authoritarianism isn’t a very good measure of government, when a monopoly on violence is one of the defining characteristics of a state. The difference is often more perception than it is reality, and even then tyrants can be vastly different from each other. Abraham Lincoln had Northern dissenters killed, and suppressed peoples rights, yet he was still a peak president.

Richard Nixon is the Shah. Saddam Hussein is the Shah. Modern Spain had death squads killing political opponents in my lifetime. Where isn’t lead by the Shah?