> The French state was less efficient, but more resilient and difficult to conquer, while the Ottoman state had more efficiency but was highly fragile.

Machiavelli is saying the opposite of what you think he's saying.

He's saying that France's governmental structure makes it (relatively) easy to conquer. Because there are many quasi-independent, competing fiefs, an invader is not necessarily facing a unified front, and may in fact be able to recruit dissatisfied lords to their cause. But that doesn't make it the kind of place you'd want to rule, because once you've conquered it, it's (relatively) easy for another invader to conquer you for the same reasons.

In contrast, there were no fiefdoms in Persia. Unlike the lords in France, the regional rulers in Persia were chosen by the state, and picked for their loyalty. When invading Persia, you are far more likely to face a united front, making it (relatively) difficult to conquer. That said, once you've conquered it, it would be (relatively) easy to hold for the same reasons.