The most important thing in all of The Prince is the stability of the state. Nothing else matters. Machiavelli doesn't care about being "nice" or "good" or moral in this arena. Actually, he was the first theorist to remind us that there is no "ethics" in politics, even though they almost rhyme. Lie, kill, and steal—it's all okay (at least up to a certain point) if it's for the sake of the state. Somehow, though, we get the feeling that most of the political actions in The Prince aren't quite as noble as that. Maybe these rulers are all just out for themselves. Either way, the goal of politics, like the goal of every single other thing in The Prince is to get what you—oops, we mean the state—want.
The ultimate aim of all politics in The Prince is to enhance the well-being of the kingdom.
Whatever the ruler wants in The Prince is the same as what is best for the nation.