The purpose of virtue in itself is not to lead to happiness, but to self worth, becoming a contributing, fruitful, and purposeful citizen of the world. If having this knowledge about oneself makes you happy or satisfied with your life then virtue has lead to this but it was not the purpose. Is it the best way to live, yes I think so. Having honor and integrity, being righteousness, considerate, striving for excellence, showing generosity, rectitude, giving advantage to others when deserved, and having and showing character gives life and your choices, dilemmas a clearer path. All of the adjectives used are synonyms for virtue. again my thoughts one should strive to be virtuous for your own sake (gives you peace of mind n the long dark hours of contemplation, lol) Your acts as a virtuous person is definitely in the long run best for you, good if it helps the community, but the community may not see those acts as what is most expedient or needed at the time, and certainly may not cause immediate happiness.
Looking at the philosophers you have listed and judging by the wording of the question I would think that the choices would be between those who spoke of happiness, pretty much eliminating Plato). Both Epictetus and Seneca were stoics believed that virtue was a way of life, is sufficient for happiness," and as such made one was immune to misfortune so , i would guess that only one of them would be in the selection. I would definitely include Machi, he is so different in that his belief was that the state was all, happiness and virtue " includes pride, bravery, strength and an amount of ruthlessness". Different from that of all the others, although all did seem to emphasize that virtue did come from within as well as without the individual. Plato believed that characteristics of a virtuous man may be the by-products of virtuousness but they by no means define virtue (conversation with Menos). Epicurus - virtue led to attaining a happy, tranquil life, characterized by peace, freedom from fear, the absence of pain, and by living a self-sufficient life surrounded by friends. what Al-Farabi believed i haven't a clue . Enjoyed the brainstorming, sorry I went on and on, but this was such a great question. I looked up all the men listed on wikipedia, and then followed some to the references found in the articles. Good luck and a GOOD grade on your project