In addressing the question of what is the chief good for human beings, Aristotle finds not a single chief good, but a pluriform goodness rooted in the individual's desire (eudaimonism). He takes issue with Plato's Ideal Good which Plato maintains is absolute, that is, the same Good for all people, at all times and in all places.
For both Aristotle and Plato the question of what good was a philosophical question, but one which could not be excised from morality. For Plato, the Good is enacted by humans who knew the Good. We might call these enlightened humans. For Aristotle, the Good is enacted by those who fulfill their personal destiny (which brings happiness). Because he saw each as having a unique destiny (teleology), Aristotle maintained that each would experience Good/personal happiness differently. One's destiny was the chief good for Aristotle and required hard work to discover.
"Will not the knowledge of it, then, have a great influence on life? Shall we not, like archers who have a mark to aim at, be more likely to hit upon what is right?" (1094a 21-24)
Aristotle remarks that there is broad agreement that the chief good is personal happiness in the fulfillment of one's destiny. This is why "eudaimonism" is often translated as flourishing. There is broad agreement that this consists in living and doing well, but beyond that there is not general agreement. Aristotle always takes common opinion seriously in trying to develop his own view. Plato sees the Good as above common opinion or common convention. It is an eternal Form existing outside of time a space and yet the natural world reflects it.
In the common view, a flourishing life consists in pleasure, honor, and virtue. Aristotle will argue that when we want honor what we really want is to deserve honor.
Related reading: Plato's Debt to Ancient Egypt; Aristotle's Observations Do Not Penetrate Beyond the Material