Despite Aristotle and Plato's differing ideas about government, they shared a

Trust in majority rule.

Explanation:

Despite their differences in politics, they have one thing in common, despise tyranny, that's why both of them believed in a government exercised by a majority, with democracy, attending to assemblies.

In words of Aristotle: "it is evident that the form of government is best in which every man, whoever he is, can act best and live happily."