The only major problem with both of them is the fact they inadvertently set their regimes up to fail after they died.
In the case of Franco, he named as his successor a degenerate monarch who had no real interest in maintaining the Francoist regime.
In the case of Salazar, he was terrible at delegating power and ultimately placed his country in a position where it could not function without him. When he slipped in his bathtub in 1968 and went into a coma, power was left in the hands of people who were both incompetent and inexperienced; and incapable of governing the Portuguese Empire.